Antenna Development - Which USB Tuner?

[nuverde]

A little over a year ago, I put together a site with some of my basic DIY antenna builds. http://www.diytvantennas.com Now I would like to add some more detailed real-world performance information for these antennas. Also, I want to play with some other easy-to-build designs and be able to post performance numbers for these too.

Can you guys recommend a good USB digital tuner that:
* I can get for under say $100
* will be able to give me good quantitative signal strength scores. The TV that I own just shows a bar scale of signal strength.
* Windows only is okay, but it would be great if it worked well with Linux "out of the box"
* even better would be if I could run a script from the command line that would scan channels and print out a table of signal strengths

Thanks for your suggestions!