I've seen them advertised before in the snappy promos. They seem rather limited in size selection. Like Dave says, Standard sizes are not common anymore.
If you need an extra deep socket, go buy two sets of harbor freight sockets, take one, chop the 1/2" square drive section off, and weld the rest to the top of the second socket. Whammo blammo, extra deep socket for dirt cheap.
Specialty tools like that are rarely worth the premium tool truck price if you can easily and effectively craft your own version from readily available materials.
For example, I fabricated a leaf spring bushing installation tool earlier today for a job I had to do on a diesel Ford Excursion. Grabbed a foot long long chassis bolt in 12x1.75mm that was lying around the shop, made some adapter parts from exhaust pipe (similar to balljoint press adapters), added some anti-seize, and presto! Bushing installation tool. Total cost? $0.00.