yeah, it totally depends on your specialty, whether you live in a city with an airline hub and good airline competition, etc. Many programs in less competitive specialties with small classes pay for hotels. I've heard of some rural FP programs that will even fly you in. One in Alaska offered a classmate of mine airfare, hotel, and $1000 to come interview. Seriously. Most of my anesthesia programs (even the big west coast ones) paid for hotel.
I budgeted $500 per interview, but any time you can combine a 3-4 city stretch, you'll save money. I ended up being way underbudget. Again, depending on your specialty, you should be able to schdule things in runs (e.g., medicine programs have like 30 dates during the season, but derm or ENT or something may only have 2, making it much harder to line things up).