I don't think it's tacky. We are in a similar situation this year and so is a lot of our family. The economy is just too iffy right now to go into debt for "stuff".

Our Christmas card this year goes something like this (haven't written it yet, so "something" like this).

.... We will not be exchanging gifts this year. We hope that you understand. Our only present to you is that we don't expect gifts either. Please don't spend your hard-earned money on "stuff" for us. Your time and love are enough for us.....