I've moved three cabooses for others. Pulling teeth with a herd of mice is easier. First, all the downers I've encountered:
Almost all of the "good" equipment is owned by brokers making very-long-term investments, capitalizing on the person with a lot of disposable income who really wants a car. They will charge what they can possibly get.
Once easy to get in the '70's, railroads aren't too keen on letting go of cabooses any more. If you can find one and can bid on one, scrappers don't like competition, and the first hoop you'll have to jump through involves payment-- Railroads want full payment on-the-spot, but won't take cash, and frown on checks-- they want an existing account. Chatting up a business that ships with the railroad and already has an account is the easiest way to get around it.
Okay, you bought the thing. Maybe you'll get a good deal on RR shipping, FOB nearest terminal, but nowadays "pay from storage location". Either way, if the RR has to move it at all, YOU pay for whatever's needed to certify it for shipping-- mostly safety appliances and brake work.
You're very lucky if you have a spur to put it on, but if the RR has any say in the matter, you need to get it completely off ROW. Even a 50-foor move involves a crane and its crew, paid for by the hour from the minute the equipment leaves the movers to the minute it returns. Expect a couple hundred bucks an hour and ROUND UP-- 61 minutes equals two hours. Remember, most cabeese weigh 29 tons.
Longer shipping? Expect oversize permits to dramatically increase crane costs. Power companies may need to lift power lines, and the novelty of moving RR equipment has worn off, and they charge A LOT. One of the 29-ton cabooses I moved punched through a substandard bridge which the township wanted us to pay for until we showed how we "patched" the hole with a triple-thick layer of plywood (that obviously worked better than the bridge), thus proving poor bridge inspection was the real issue. The now-defunct Iron Horse restaurant chain figured out how to move cars using equipment similar to what moves mobile homes, but I haven't seen the equipment, and can't find anyone who has (worthy of someone looking into).
Of course, you have to find a co-operative zoning board. caboose #1 was considered a "shed." No fooling! Cabooses #2 and #3 had to be set on a cinder-block foundation, because of a fear that, if on trucks, they would roll away! Idiots! And don't forget the NIMBY and idiot factor; Caboose #1 generated protests because of a misunderstanding of what "trucks" were.
Make sure you have a disposal plan in case the RR gets abandoned or you decide you really won't live forever. One caboose in N Michigan has been for sale for almost 15 years now. Not everyone wants one, and location is a very big deal. Some old GT passenger cars N of Petoskey, MI are now tourist association owned, who got them for almost nothing after PRR/PC/MIGN pulled up tracks. I shudder at the thought of moving an 85-foot passenger car any real distance.
Cupolas are useless. They're not a separate room; they're just a higher part of the roof, with equipment lockers added in the space on either side, with seats bolted on top of them. Try turning a cupola into a kid's "clubhouse" means ducking down to get from the front of the caboose to the back, and the little ones will quickly outgrow it.
THE GOOD SIDE:
You CAN find that great deal saving you a lot of bucks, if you can wait. I know of one caboose locally (Grand Rapids, MI area) that was bought and moved for cheaper than a substantial storage building would have cost. Considering it as a guest house or vacation cabin and the price and work is easier to swallow. Especially if you're not one of those people who whine about problem lists afterwards.
As for personal satisfaction, hey, I saved three cabooses from uncertain futures. NYC, C&O, C&NW.
ALSO, put simply, YOU NOW OWN A RAIL CAR. How cool is that?