Need to buy/build a content filter for a school

[nightowl]

Is there a company that makes a relatively inxpensive (less than $300) content filter, or is there something for Linux or another OS that I can build out of a spare box. This is for a small private school (I attended there for 1st-8th grade) and money does not exactly grow on trees (reason I suggested building a box). It will be connected to a DSL modem and from there to the rest of the network. Any suggestions will be greatly appreciated.

 

[FoBoT]

put in a pc running Clarkconnect
it has an option for a content filter and you can subscribe to get updates for a reasonable price

also, e-smith/SME server includes squid proxy server , which can be configured to do content filtering, i've never done it myself