My rule of thumb on equipment is I only buy used if I can inspect it and operate it myself, and it has to be within a 3-4hr drive. I realize in some parts of the country you don't have that luxury, but I've always found any piece of equipment, truck etc within a 200mi radius of where I live. Sometimes you have to look for awhile, but something good always comes up eventually.
If there was some specialized piece of equipment I needed far away I'd gladly take a flight out to inspect it and do the deal in person, then arrange to have it shipped back. The cost of a plane ticket, rental car and possibly a hotel are cheap compared to losing tens of thousands or hundreds of thousand of dollars on a scam deal.
All that being said, skid steers and CTL are plentiful and everywhere. You should have no problem finding a decent used machine within a reasonable drive. It may not be 'exactly' the machine you are looking for with 'every' feature you want, but that's part of buying used.
In addition to excavating I'm a builder myself and have both a wheeled and tracked skid steer (CTL.) Aside from good reliability, the things I look for in a machine to use around a building site are 1) enough lift capacity to lift a full pallet of block, pack of sheathing etc, 2) easy to get in and out of, 3) good visibility, and 4) good stability and flotation. Case, Kubota or Takeuchi are my top picks. Deere also makes good units, Cat and Bobcat could be good as well depending on the year/model.
