An external USB enclosure for a 2.5" ATA100 or SATA drive should be about $15.
If you want a dedicated purpose thing without the enclosure, this actually costs more, but is a useful thing to keep around:
http://www.newegg.com/Product/Product.a ... -_-ProductIt's the guts of an enclosure, sans enclosure, with the ability to plug into 40-pin ATA100 3.5" HDD, 44-pin ATA100 2.5", and SATA.