Although Jason has already made the ultimate offer, there are several options:
David Gage: 24 hr. rentals - expensive but (hopefully) a mature instrument (
www.davidgage.com)
Bassgarden: As mentioned above this might be the best solution since you'll probably get a decent instrument for a fair price if it's only for a day or two (
www.bassgarden.net). The shop is in Yonkers, about 30-40 mins from Grand Central Station on the Metro North train.
Kolstein: I once rented a bass there for an entire year (price for a college student: about 1 k per year), got a very decent instrument, not sure about his options for short-term rentals. (
www.kolstein.com)
Good luck with your audition, I played a private session at City College yesterday night, studying at Manhattan School myself....
All the best,
Johannes