I just did the bucket tilt cylinders on my Cat 931B, they are 3-1/2" bore cylinder with 2" shaft and the shaft is around 36" long.
As I'm semi-retired and not super-rich, I wanted to keep the costs to a minimum.
I removed the cylinders myself (20 mins each), took them fully apart myself (they're a simple design with just a screw-on crown on the cylinder, and a single 1" bolt holding the piston onto the shaft).
That took me around another 45 mins (each). Then I removed all the seals (some fell out in pieces), and pressure-washed all the components, and then examined the cylinder bores.
They were in fairly good shape, with the important feature being no long scratches or scars inside the bore.
I then ran a ball hone through the entire length of the cylinder for around 15 mins, until I was happy with the smooth finish. Not all cylinders need stone honing, they have to be very badly worn to need that.
The shafts were in poor shape with a lot of scores and gouge marks (from gravel and dirt falling over the back of the bucket), so I decided they needed replacing.
I went to a local chrome shafting supplier and picked up 2 x lengths of 2" chrome shaft for AU$200 for the two lengths.
A local hydraulics repairer had quoted me $300 to cut each eye off the old shaft and weld it to the new shaft - but I gave the job to a semi-retired buddy who has excellent machining skills (and who needed the work and the money) - and he cut the eyes off, welded the new shafts on, and drilled and tapped the hole in the inside end of the shaft for the retaining bolt.
I paid him the same money - AU$600 for the 2 jobs.
I picked up 2 new genuine Cat seal kits for an average of AU$50 each (one off eBay and one from a local NOS parts dealer) - fitted all the new seals and re-assembled the cylinders.
All up, probably about 4 hrs re-assembly work in total, and they're finished and ready to re-install - which will take about 1/2 hr.
So, the total financial outlay for me, for these two bucket tilt cylinder repairs has come to AU$700 (plus a lick of paint), and around 2/3rds of a days work on my part.
I don't place much value on my time, but even if I paid myself $500 a day, the whole repair job for the 2 cylinders would still only be around AU$1000.
I also needed to replace the 4 flexible hydraulic hoses that are attached to these cylinders - but I had a roll of new Gates 4-spiral wire hydraulic hose on hand that I'd bought cheap at auction, so I cut off 4 sections of the correct length, and took them to a hydraulic hose repairer/supplier, who supplied 4 new hose fittings, and who crimped them on as part of the deal.
The 4 hoses cost me AU$280 for the supplier to supply the fittings and crimp them on.
I guess if I had to pay someone to do all the work I did, I would expect the cost would have been over AU$2000 for the 2 cylinders.
When people supply their full services, you need to help pay for all their tools and equipment they use on your job.