Is this about right for a hen do?

[Jingleboom]

2 nights in Leeds for £170 - includes accommodation and one activity (other activities extra)
The bride is lovely and I'd love to go, but I've only known her 9 months and tbh I've never been on a hen do before and am a bit nervous.
On the plus, I'd have to buy going-out outfits inc shoes and bag as I really have nothing
I could afford it, but only just & also could very much spend it on other stuff
Not sure if I have an AIBU, on here for traffic

Hell no! You know this is the minimum price you'll pay... Most likely it will double at least. Back out now.

It may very well be more expensive. Check whether you can opt in or opt out of the activities in advance, as there may be some activities that are non-refundable.

I organised a hen weekend a couple of months ago, and was told by another organiser that I shouldn't expect the weekend to cost less than £250 per person. In the end, it cost around £280 per person.

Ah that will be the price before you find out you are expected to pay a share of the btb costs. . The strippers +extras (), taxis, rounds of drinks, burger van /kebab on the way back, cleaning of taxis after bouts of vomit /or worse. Bail costs when someone is arrested /fined for d+d or worse.

Cancel ASAP. .

I've never been to a UK hen do, but I've been to a few bachelorette parties in the States. I agree with honey that's the minimum you'll need to pay. Just think of all the meals and drinks out. In the US the bride doesn't pay for anything, so you're also paying for her to eat and drink. If I've only known you for 9 months, I'm unsure I'd go and spend this type of money.

In terms of cost, it is a 'how long is a piece of string' question, but I'd suggest you are wary of going on a hen do with someone you've known for such a short length of time. Some people have odd ideas of what you have to do to "enjoy" a hen weekend.
It does seem likely that is just the start of the cost though - after the accommodation, there will be food, drink, maybe taxis, entrance fees, sometimes a costume or 'prop's for fancy dress / games / activities.
Have you found out what they are actually planning to do once there ?
Keep in mind there is NO obligation to go, unless YOU actually want to.