To not buy much for adult step daughter for Xmas?

Specify a budget too eg we are spending x amount per adult this year.

I wouldn’t be sending expensive gifts to someone who cant be bothered to see me for 18 months. I’d just tell her to send another list with less expensive items on because you’re cutting back this year.

Cheapest thing £170, just wow. I'd suggest to her Dad he buys her gift voucher for Amazon. Is she planning on coming over to see her Dad or sibling? Will she bring them gifts? Perhaps you should all send her your wish list to show her how rude she is. She needs to learn ignoring her sibling and Dad's birthdays have consequences. As for the wish list for her boyfriend I'd send it back with the message 'You must have sent me this by accident, I've never even met this person'.

Reply to say, ok sent on to dad , do you need ideas for him/siblings ? Or have you already bought stuff?

So you (collective you, not you) have always bought everything on her list and more and yet this year you are wondering why you have a selfish, spoilt brat on your hands.

No adult should be sending Christmas lists to another adult. Her parent need to have a word with her about this, no matter how uncomfortable it is.

Expensive presents can be sold for cash for drugs op

Just reply as a working adult we don't do huge lists, we'll do the usual of token gifts up to £x.

And I'd buy socks for the bf

I'd be jumping on the good relationship with mum and decide together what you all do as a united front type thing

Does she want to/has she ever come to yours for Christmas? Might be another way of opening a conversation.

Whenever I'm wondering how/why some people can behave so thoughtlessly, I read a thread like this and understand.
If people constantly make excuses for others' bad behaviour and don't call them out on it (there are ways to do this kindly, calmly and assertively), then of course they're going to continue. Handing this one back to her father isn't going to solve the issue as he and his ex are actually the ones who have enabled her attitude in the first place. Yes, many teens can behave thoughtlessly and selfishly but it's our job to lead them through it from the first day it rears its head. No way should this have been allowed to escalate like this.
And the poor OP has been landed with it (the product of other people's bad parenting).

Message her and ask if she would like a list of ideas for her dad and mum/siblings as you've thought of a few if it's helpful.

Oops
Instead help her but educating her aunt's adulting.
Should be help her by educating her about how to adult.

"Thank you for the wish list. Here are ours."

Seriously, that. It's simple, with no emotion or criticism involved.

Or if you want to be more conversational :

"thanks for the wish list, I've passed it on to dad as he's doing the shopping this year. If you're wondering what to get us, I have some ideas that are easy to post. Dad would actually love a book token, and (step sibling) would be ecstatic with a token or money to spend at Smyths..." etc

Don't make the Christmas list about her contact over the last year. That will set you all up for a transactional relationship going forward. What it says if you visit then you get expensive presents.
Instead help her but educating her aunt's adulting. Adults don't send unasked for ridiculously expensive lists. If someone asks for suggestions they may send some, and they'd think about the other person's financial status and previous gift giving and tailor the list/costs appropriately. Someone (both parents) need to tell her this.
Someone also might want to open a conversation about missing seeing her? And ask what she might want from an adult parent child relationship going forward and/or her sibling.
With regards to what to buy her. Buy her something you think she might like that you can afford...

She doesn't sound like an adult, more like a self absorbed spoilt teenager. If anything then a very small token gift like chocs. Ignore the list and do her a favour by not pandering to this unpleasant sounding person.

We have a family WhatsApp, and one of my cousins had been mostly out of touch for a year or so (no acknowledgements of birthdays/Christmas, no cards or gifts).

He then sent his Christmas wishlist to the group chat and my aunt (not his mum, a different aunt) replied pretending to be confused, saying she’d thought he’d decided not to do gifts anymore as he hadn’t sent any of us cards or gifts in a year, and that she was fine with us not bothering to do gifts for grown ups/wider family if that’s what he wanted.

he ended up apologising to everybody - he’d gone through a bit of a depression and bad breakup and just hadn’t been thinking about everybody else.

i’ve always admired that fake confused message!

her and the boyfriend sound like they have a "party" lifestyle and that will be contributing to her thoughtless its not an excuse though but .you are all letting her act like that do either someone says/does something or they don't. she isn't going to miraculously change .

Me and my adult sister give a "list" to our parents and they usually write one too. Nothing amounting to hundreds of pounds and no expectation that you'll get it all, just to give people ideas of what to get. But obviously it's all reciprocated and no one takes the piss

Can you introduce an adults secret Santa? Where each adult buys for one other adult with a budget of say £100? You can include her boyfriend if he wants to exchange gifts. We do this in my family as there are lots of adults and it's a way of making sure everyone gets a gift each. As nieces and nephews reach adulthood, we invite them to join and it's up to them if they do. If they don't, their gifts stop though as we only buy for children or those taking part in the secret Santa.

She's an adult as you say. She lives independently.

I'd tell her straight you didn't send anyone so much as a birthday card this year so you'll not be getting anything from your list and nothing at all from your boyfriend. I'd tell her she'll be treated the way she treats everyone else.

You live by the sword, you die by it.

box of Celebrations between the two of them.
One of those big tubs if you're feeling generous.

No way! IF, as some have wondered, there's a possibility that they are intending to use the Christmas gifts as funding for drugs, sending money is the LAST thing I'd do. Why make it easier for them?

I’d spend the same as the other kids are getting from you. Small gift for new boyfriend you haven’t met.

I would send her cash. That way you've given her something, you can say it's for both of them, and it sends a message that no effort will be given if she can't reciprocate.