So we went shopping for used 4wd tractors. The ideal for our budget was a 30-40 HP diesel tractor with a front loader and a 3-point hitch, in good condition with less than 3,000 hours on it. Here in Washington those are rare. Tractors we found were either high priced ($15k+) or high hours (6,500+).
After a few weeks of searching, we checked into new tractors and found that they were not that much more expensive. $15k gets you a nice new tractor with a warranty. $17k gets you a hydrostatic transmission, sun shade, tire upgrade, ballast in the rear tires, and delivery. Kubota was offering $0 down and 0% financing for 42 months. It doesn't get much easier.
PHOTO: We bought a Kubota L3400 (35 HP, 4wd) with a front loader. It's a small farm tractor, very popular with orchardists in this area. My brother makes the tractor look even smaller than it is: He's 6'8" tall without his hardhat.
The tractor has enough power for about 90% of our logs, and usually we can buck the big logs that make up the other 10%, or use a block and tackle, to make them skiddable. Its light weight is an issue in the soft dry soils where we're working. The machine routinely loses traction, but in 4wd with the differential lock engaged, it's more likely to stall than to spin out all 4 tires.
We attach 1 to 3 logs to the lift bar using short chains and grab hooks, or sometimes a small grapple. Lifting the bar raises the butts of the logs off the ground, so skidding doesn't disturb the forest floor and tear up roads as much as it otherwise would. (There's still a lot of impact.)
PHOTO: Looking down from the tractor seat while my brother loops a chain around a log. The chain has a slip hook on one end, to connect tightly around the log. The other end goes into a grab hook connected to the tractor's lift bar. We carry two of these setups on the lift bar, plus a little grapple that I can sometimes drop onto a log without dismounting the tractor. The grapple tends to release unexpectedly en route, but at the end of the trip it rarely comes off the log without my help.