Andy,
I was hoping to hear some crane experiences from others too before chiming in my 2 cents.
I found a 15 ton 1974 Grove Rough Terrain crane for $7,000. It has a 60' boom (plus 20 foot jib that I've yet to use or need). Starts and runs any time I need it. One cylinder inside the boom leaks (got to finish this house before I tear the boom down!) and the transmission is weak and the brakes do not work (but the parking brake does work). So far I've had to replace two hydraulic hoses and the battery. Other than that, it's perfect.
Some thoughts...
All of the timberframe companies that I spoke with (before deciding to build my own frame) just pass the crane bill on to the clients. Not a bad arrangement if you ask me. If you're in the timberframe business and your clients are tolerating the crane bills, I don't think I'd mess up a good thing and get into the crane business.
With that said, maybe there are good reasons for owning a crane. For me, the reason to buy a crane was that between pouring basement walls, building a bridge, erecting a large frame (and taking forever to do it), hanging panels, and putting 43,000 pounds of slate on the roof, I was going to have a lot more in the rental than I did in the purchase. Of course, if nothing big breaks, I can sell the crane when I'm done and possibly break even, since my model crane is "at the bottom of the depriciation curve" as they say.
Some things to be aware of if you buy a C60 w/ 8ton crane... if it's road worthy and you plan to drive it on the road, you'll have to pay taxes and insure it for the road and I'd bet that costs a fortune. A lot of times, it'll be sitting idle and you'll be paying that insurance. 8 tons is not likely to be enough of a crane for every project you take on. For my house (oak frame, 2 1/2 stories), the 15 ton crane was just barely enough at times, even when raising many of the bents seperate from their trusses. What you end up with are situations where you can't get the crane as close as you'd like, and you end up boomed way out, where the lifting capacity of the crane is meager. (a 15 ton crane will not safely lift 2 tons when boomed out 60 feet) So you could find yourself in a position where you've sunk a chunk of money into a crane, you're paying insurance on it, and now you have to park it and rent a bigger crane. That would not be rewarding.
So if I haven't talked you out of a crane, I guess I'd suggest considering a rough terrain crane (won't get stuck in the mud, 4wd and 4w steering so it can crab right next to the house site, doesn't require road insurance or taxes) of at least 15 ton capacity. Yes, you'd have to pay someone to move it from site to site, but this would probably be cheaper than the insurance on a crane that can drive over-the-road if you're not planning to erect a frame more than once every two months.
Here's a picture of my Grove...
you can see other pictures on my
blog