how much do they cost to buy one new?
I wanna say around $350? They can be bought used for a little less. They do hold their value well and seem to crash pretty well yet.
Rentals are usually around $50, so, it doesn't take long for one to find a good reason to own one if the racing body uses them. I wanna say that CCS paid around $300 each for their transmitters for the dbcom set up they use.
Then there's mylaps.com. Usually, the organization posts up times on that site. Not sure if there is a cost on that or what exactly. Probably is, but it's nice. We've been to Brainerd on a Saturday racing, and then looked at our times and those of competitors that night. All depends upon them being uploaded. You can get results that way. Not perfect, but it's usually a pretty good indicator.