go to zinn cycles and scroll and you will find some different chain ring guides if i remember correctly.
if you have shimano
you can use
12/25 Cass.
12/23Cass.
with 50/39 chain rings
50/38 chain rings.
50/36
also you can use chain rings by salsa/sugino and others to customize your own configurations.
there needs to be no more than a 14 tooth difference if you want to use your existing crank and front derr.
i don't know how hilly the area is that you live but just some ideas of possible changes without spending alot of money.
also check this site out you can configure your own and see if they will work
www.jbarrm.com or
gear inch & shifting calculator