I have a Blackberry with Verizon, but is it possible to get the internet from an outside provider? My Verizon rep says it'll cost me $45 a month to add the internet onto my blackberry, so I'm looking for a cheaper way to do this. Any advice would be very useful.

Wirelessly posted (Opera/8.01 (J2ME/MIDP; Opera Mini/2.0.4509; en; U; ssr))

Welcome to Verizon. The only way to get it cheaper is to choose a carrier that has less expensive data IE t mobile...

Nope. Your carrier is your pipeline to RIM's network and then to the internet. Cingular offers a BIS-only Blackberry data plan for something like $29/mo. TMO's BIS add-on is $19/mo with a voice plan.

T-mobile is pretty cheap I think.
Sprint is 39.99 right now and unlimited phone as modem (I was getting 1.2 mb last night on EV-DO so its worth it)