Airfare:
$200-400, maybe more, per school. Try studentuniverse.com.
taxi, bus, gasoline:
Depends. I'd allocate $50, if you don't spend it all, keep the rest for the next interview.
food, hotel:
Stay with student hosts!!!
interview clothes
If you're a guy, go buy a sport coat, some slacks, a pair of shoes, a dress shirt, and a tie. Maybe $150 - $250 if you go to the outlet store and aren't too picky (basic black, slate gray, or navy blue). If you're a girl, I don't know.
MCAT training :
Buy Kaplan Comprehensive Review. That's it. $65.00 on Amazon, can probably get one locally or on Ebay for a lot less. Seriously, don't waste your money. The MCAT costs $190. Practice MCAT's, I'd allocate $100. You get one free with the Kaplan book, you can probably get them off Ebay pretty cheap.
application fees:
Figure a total of $150 per school, including AMCAS, secondary, and sending your LOR's.
gifts and cards:
Too late, already broke. :-( Buy a postcard if you can. That's it.
I live in the midwest, our cost of living is very low. So actual mileage on this may vary. Needless to say, it's expensive.