I asked this question on the BitTorrent mailing list a few months back. I was directed to the
"Linux Advanced Routing & Traffic Control HOWTO", which will work if you're using Linux and acccustomed to harder-core sysadmin stuff than me.
You might also want to look at mod_proxy and mod_throttle for apache. The learning curve should be pretty kind (a 'make' command or two, and a few lines in httpd.conf) to get it proxying and throttling your AOLServer.
FWIW, IIS also supports bandwidth throttling in it's management gui. I have no experience with it, so I can't tell you how, or how well it actually works. But if you have a small business license to back office, MSProxy will probably support the same functionality with probably the shallowest learning curve of all.
My suspicion is that after looking at all this, $25/mo will start to look pretty good. 😊
