I think it is so great that you send money to your family so that they can have a large Christmas dinner! I like that you are thinking of different options of what to do.
Here are some thoughts of mine that might trigger other thoughts of yours... could you make something, sew a cute bag, make a batch of brownies (if a box of brownie mix is on sale, it can be under a $1, I don't know if that is still out of the running), other homemade gifts, or 'kits' ... the ingrediants for them to make their own brownies (all put in a glass jar) or a soup mix (same glass jar idea) or beaded necklace kit with a ribbon or string and a a bunch of beads or some choice few.
CraigsList.com or 2Good2Toss.com or FreeCycle.com are some great places to get really inexpensive items or even free (people just want the stuff out of their house sometimes). Or even me, I'd be fine with letting you just have some fabric.
Another thought... the gift exchanges, is it a "White Elephant" gift exchange? Those are supose to be just stuff that is lying around your house (unless they say otherwise), makes for great fun. I actually got some great gifts at White Elephant gift exchanges... rollerskates, a cheapet that one of my kids wanted one year (it was never opened), and an new apron that the owner had just never worn (last years gift manybe).
If they are good enough friends to invite you to their Christmas party, and they know your finantial situation, then I'm sure they would WANT you to let them know that you are thinking of not coming because of the gift thing! The host of the party usually? (I do) have extra gifts there on the ready for those who didn't bring a gift.
I know that it is not part of your question, but with the 'not giving you husband a gift'... what if you wrote him a letter, thanking him for all he does and what he means to you and ... you know. You probably aready do that, I just thought I'd put it down. Actually, that was one of the best Mother's day gifts I ever gave to my mom and mother-in-law and grandma's. I started with just a plain white piece of paper and just wrote any good memory or good word or thoughts or thanks... I drew simple flowers (I'm not an artist) in the corners and green lines in between the flowers with markers to decorate the paper. Each 'mom' was crying when they thanks me saying that it touched them so much. Okay, enough of memory lane for now.
I have no dought that others have written wonderful ideas and I'm going to read them and get some ideas to use for me.