Bandwidth mod/limit

am currently running several free webbased (open) proxy sites. I need a bandwidth limit per user/ip. This can either be a script, or a mod for apache, or anything else that will do the trick. I want to be able to control howmuch bandwidth a user ( or IP adress) can consume over 24 hours ( limit the traffic that goes TROUGH the proxy Up and download) My server is connected via a 100mbps line to the internet. I dont want to limit speed of up and downloads, but i want to be able to set a hard dayly BW usage limit per day. You can find more info on the Proxy script im running at: [login to view URL] Money will be escrowed and released AFTER installation / testing on my ( dedicated) server ( 3 proxy sites). Budget for this project is between 100 and 400 dollars.