Hmmm. I don't have the solution your asking for, but have you checked out iButtons? (www.ibutton.com). They look really cool and I've been wanting to play with them for months now but havn't found an excuse.

One of the many buttons they offer is a time/temperature logger that can actualy be seperated from the computer. For your purposes I'd assume you could just tape it to the reader and forget about the mobility aspect.

The starter "thermochron" button kit is $25, which seems to be a much better deal than what you've found so far. Let me know if you try it out, I'd love to hear how they work in practice.

Matthew