I appreciate everyone's responses!
I got a list from her the day after Black Friday
Two shirts for her, two shirts for BIL. That's it. She said, "if you don't get everything on this list, let me know so I can send it to my sister." So eventually I will either have to tell her, yes, I got everything on the list, so now you know what you're getting, OR no, I didn't get you everything on the list. She makes my teeth itch.
I decided to buy my DH an Xbox and the Skyrim game that he wants so much, because he's a good DH and he deserves it
I told my MIL and SIL that I was buying it, and that it was $250 total, and if either of them wanted to chip in, that could be their gift to him this year and it can be from all of us. MIL is chipping in $50, but SIL refuses. First she had to tell me that she saw an Xbox 360 at Target on Black Friday for $139 (thanks, that helps me not at all because it's not at that price here or anywhere online that I can find), then she said she'd get him another game (thanks, but the only one he wants is the ONE I ALREADY GOT).
I don't know why she resists everything I do or say. It's very frustrating!