I really like my Supco SL300T. I've had it for 3 years and the battery is still good. It had a USB hookup, not serial like the older Supco's. I use it mostly to prove tenants are just trying to get a new fridge from the landlord.
My supplier has them for $62.99 wholesale which is the best price I've seen. If you decide to get one and can't find a better price, let me know and I'll have them drop ship one to you.