Apologies for the premature Christmas related topic.
Also, sorry that this is quite long and a bit like one thing after another, just don't want to drip feed so have tried to get all of my points in.
DPs mum separated with her husband about 6 months ago, but they still live together. She is apparently moving in to a new place with DPs younger sister (13) by Christmas, although I can't really see this happening, as she isn't doing anything about it.
DPs original plan for her Christmas present was presented to me like this:
He, his brother, his brother's DP and myself would put the money together to get her a car that she wanted. DP was thinking it would cost about £600 so £150 each 
I said I wouldn't be able to afford it. Turns out the cheapest you could get that particular car for was around 2 grand so that isn't happening.
Now DP wants us to put money together to buy his Mum a TV for her new place as she won't have one. He says this will cost about £100 from us and the same from his brother. Now I know DP and he will look at TVs that cost £200 and decide that they aren't good/big enough, and so will want to get a better one, he did this when we moved out and were looking at TVs.
I told him last night that I didn't think we should be buying his mum a TV for Christmas, as it's too expensive, and he seemed mightily pissed off.
I'm not just being a cow, there are a number of reasons I feel this way.
We are both students, work part time (I am on Maternity Allowance at the moment) and have a 14 week old DD. We are constantly having to shop around to find things we need for DD for the cheapest amount possible, we don't splash out on the nicest things as we can't afford it.
The reason that this is really pissing me off is that he currently has the car my mum gave me (I haven't yet passed my test) as his is on its last legs. He was supposed to sell his car and buy a new one, which he hasn't done (has had around 5 months to do this) as he says he can't afford to buy a new car even with the money he will make from his.
Also, if I suggested spending £100 on my mum for Christmas he would flat out refuse, and say "she's loaded" (she's not) so she doesn't need it. Never mind the fact that she has spent around £2000 on DD, provided us with so much that we couldn't afford and on top of that has offered to look after DD from September while I go back to Uni. For free.
I wouldn't ask to spend that much on my Mum because we can't afford it, so I don't see why he thinks it's ok to spend it on his mum.
We are also going to go down to stay with her over Christmas (we live up north, she lives down south) which will cost us at least £200, probably a lot more because DP will insist on buying her loads of stuff while we're there.
Granted, she doesn't have much money, but she can still afford to smoke and drink, she has an iPhone contract which isn't cheap, so I'm sure she could buy a TV if she really wanted one.
Another thing that is annoying me is that it was DPs 21st birthday this year and she didn't get him anything, not even a token gift. She sent him a card, with incorrect postage, so he had to go and pay the post office to get it.
I am not against getting her a few nice gifts, but am I being unreasonable to say NO actually I don't think we should be buying your mum a tv for Christmas and having us there for DDs first Christmas is enough?