The person that told you that BGP requires a lot of ram was probably referring to the full internet BGP table. I doubt that you would want to run this, as it would probably use up most of the connection to the internet just in updates.
If you can have your ISP send you a default route aggregation, and you just send your network's info, that shouldn't need much horsepower to run.
http://www.sprintlink.net/policy/bgp.html is a link to sprint's bgp policy.