Amy — I got some PEM2 dataloggers recently as part of a grant (and I love them!). I also was confused about the expensive USB drive and tried just using a regular flash drive I had at my desk. The regular flash drive works fine! I think if you had a lot of loggers or left them alone for a long time without pulling off the data you would need to make sure you had a flash drive with enough storage space, but it looks like any kind of drive will work.
