inexpensive url-filtering db

[rekordmeister at gmail.com (MKS)]

Hello list

Now I'm looking for an inexpensive url-filtering database, for integration
into a squid like solution.
By inexpense I mean something that doesn't cost $50k a year.

If you have references for me, feel free to contact me on- or off-list.

Regards
MKS

Perhaps there is another mailing-list more relevant for this kind of issues?