I can't imagine the drive shaft breaking, but they do list the "gearbox" as a possible explanation. I haven't gotten into that, but remember a thread where someone looked into replacing the grease. Based on the parts diagram (partstree.com) for the model 291 60" mower, the gearbox unit looks pretty straightforward. You might get lucky and need only a half-moon (woodruff?) key for the pulley.
The rust on the foot rests is quite common due to the "nubbies" on the bottom of the rubber treads. It's easily repaired. Paint is available in a spray can at TSC.
That's a heck of a dent/damage to the left fender, but really rather superficial.
The tractor looks to have only the single hydraulic (center) lift. This means that there are no hydraulics for a front lift or rear three point hitch. Adding in the optional hydraulics is quite expensive, but Johnny Bucket makes an electric front lift to fit the 3000 series for their (terrific) products.
At my local dealer, there are two of these going for $3000 +- 500 depending on age/hours and size of mower.
I bought mine with a tiller, snowblower, full hydraulics, wheel weights, chains and 3PH/trailer ball adapter for $4500. I didn't know what I was buying at the time, but found that the oil around the transaxle was due to leaking bearing seals and was why the dealer was auctioning it off. That's a few hundred in parts to replace, but it's hard to get to and not worth a dealer's labor. I'd ask the seller about any oil leaking from the rear as that would be an unpleasant surprise.
The tractor is pretty easy to work on. Mine has 800 hours now, mostly mowing and there's been some wear in the wheels/rollers on the deck. I've replaced most of the bushings at this point. That's the nice thing - these decks can be rebuilt!
Depending on the price it goes for this could be a very good deal. The cut of the 60" mower is incredible. IMHO it works best with OEM blades.
The electric lift Johnny Bucket Jr with extender would be a great attachment for this unit and would allow you to move and carry all kinds of things including mulch, brush, stone, landscaping materials, etc.
There are several very knowledgeable people on this forum who've done a lot with 3000s, so ask away.
When I moved into this house, which has 2 to 2.5 acres of mowed lawn, there was(is) a guy across the street with a Ferris ZTR - WOW!! I'll admit to a severe case of mower envy. My little 42" Husqvarna took 150 to 180 minutes of mowing time.
This year, we both had mulch delivered. He had one truck load (8 yrds) and I had a two (16 yrds) delivered. With the Johnny Bucket, my mulch was done in about 10-12 hours. His pile lasted three weeks.
Each lawn and set of needs is different. As I looked deeper into what I really wanted - which wasn't my Husqvarna 42" mower - I realized that wide and fast was going to be "it". I have very few trees and big long runs. That nixed any advantage of a ZTR for me. At 8 mph and 60" wide, the 3225 had the capability that I wanted. The uncut circle with this mower has a diameter of about five feet. I simply arranged the mulch circles around the trees to be that size so that I don't need to back and fill.
Coupled with the Johnny Bucket, which came a couple months later - used from Craigslist! - I can't believe how handly/nice this combo is. I mow my lawn in about 70-75 minutes - and get on with life. When I can't get to it, the other members of my family don't mind mowing because of the power steering.