If you decide on going with a Delorme unit I would recommend staying away from the USB version and going with the Bluetooth (BT-20) model. Myself and Chris Collura run the Bluetooth unit and are both happy, or at least I remember Chris being happy once he had everything running smoothly last spring. I know of another chaser who runs their GPS over Bluetooth and they are happy as well (Stephen Locke). I cannot remember off of the top of my head the exact details with the Delorme USB unit (LT-40) other than a couple of years ago there were some folks who bought those and ended up not being able to use them with GPSGate, as the software wouldn't pick up the signal. It had something to do with the proprietary format the Delorme unit sends the GPS signal in and the serial emulator Delorme was using was not compatible with 64 bit operating systems, which are becoming more prevalent these days.
The Globalsat unit Wes spoke of seems to be a popular puck FWIW and a lot of chasers go that route. If you want to go wireless though and your laptop supports or has Bluetooth built in, I can probably dig up a discount code that I could send you to get the BT-20 bundled with the Delorme software for cheaper than what you see on their website. If you are truly interested, you will probably be able to refer to some old threads I could link you to on the installation process and getting everything to work seamlessly on the first go around. Let us know which way you are leaning if any at all.