What ShadowAce is talking about is an HP JetDirect box. I have 3 at home that were retired from use in the company I work for. The plain vanilla JetDirect boxes are kinda hard to come by nowadays. Probably can find one on ebay for cheap.
The new ones all seem to be referred to as print servers and most have a bunch of bells and whistles that add to the price.
A quick search on the computer equipment website of your choice for "print server" will probably turn up something to fit your need and budget. TigerDirect has like 27 ranging from $25-$300+. Brand names are of little consequence anymore (it's all Chinese slave labor made) and you'll find a wide range of opinions here about which is best. Be sure to check the online reviews that almost all these sites offer now.
Thanks everyone. It looks like I have numerous options and lots of research to do. Cheers!