Marcus,
There are different types of machines for different applications. The biggest difference is wether they are directional or not. Directionals you steer and non directional have no control over the machine once started.
We got into boring 15 years ago with a partner. It was a constant headache. The successful (profitable) bores were few. The partner went on his own as a 1 man operation with 3 nondirectional tools and made a living for several years. Traveled most of the east coast. He got out once the technology caught on and every contractor started getting their own.
Imagine getting a tool stuck under the middle of a concrete highway. And you bid $60 a linear foot to go across an 80' section pulling a 4" pipe. The machine is worth $12,000.00. The cost to retrieve is, permit, bond, traffic control, cutting highway(8" asphalt and 12" concrete) excavate and (hope tool is where you think it is)find tool, backfill, compact, Drill and dowel concrete repair, pour concrete, asphalt highway, Return in 1 year to make any repairs to patch.
If you'd like a free tool to start out I can show you where it is.
That story aside boring can all be about where you are from. If you live where there is all dirt or sand it is much easier and very common place. If your in Most of New England where there is a lot of rock and very mixed soils it's a very different situation
There are sites on the internet for "underground boring contractors" and have a lot of information.
So who are you, where are you from, and what kind of work are you doing now Marcus?