While out of warranty pricing estimates exists (see link here), it is possible a bent iPhone (depending on the severity) could be considered "beyond economical repair." In that case, it may not be eligible for repair or replacement, even at the out of warranty pricing.
I recommend setting up an appointment at an Apple Retail Store, Apple Authorized Service Provider, or sending your phone in to an Apple repair facility for inspection to determine if you're eligible for out of warranty pricing. Visit getsupport.apple.com to view your options for setting up service.