Is this standard or spewage?

Here's my situation:

I'm 21. I have a serious gf who I've been with for a shade under a year. For various reasons including a broken down car I'll probably be spending x-mas with my gf's family (who I get along well with).

My family and I are not too keen on x-mas and usually don't get each other stuff. I haven't got anyone (except for my gf) anything as of yet and have no intention of doing so. My gf said her Mother got me something. My gf got her family stuff already.

I'm considering offering to give my gf half of what she paid for her family's gifts in exchange for putting both our names on the card. It will cost me ~$80, which is not that big of a big deal to me. It will be awkward and I may end up looking like an ass if I don't get anyone anything even though I'm spending x-mas at their house. On the other hand absorbing half the damage of x-mas seems a little excessive considering I'm not close to her family and haven't even got my family anything.

My time is worth ~$16/hour and I'm in no financial trouble. What's my play?