I really want to. I have a bunch of people I used to play CS:Source with that all play TF2 now. Unfortunately, I'm also incredibly broke and will be for the foreseeable future. I even cringe if I eat McDonald's more than once/month.
Maybe I should add a cheesy paypal link to my sig that says something like "Help f'lar buy TF2". Nah-- video games are so far down on the priority list.