I'd paid $1500 for the 14T which was maybe a bit much considering some of the wear and tear but I was in a hurry and there weren't any other choices, but it worked well after some typical maintenance. I learned a lot, including why it's important to make sure the plunger stop is working properly. A spring broke, the knotter clutch slipped leaving the needles up, the plunger-driven hay hit the needles and folded one over... DOH! As a bonus I learned how to build a makeshift forge big enough to heat a needle and straighted it back out. I sold the 14T for $1350 at the end of the season when I got the 24T (I didn't want 2 balers to store over the winter). I paid $750 for my 24T and consider I got a fantastic deal on it.... and it came with a spare needle!
The 24T bale chamber was less rusty and deformed than the 14T, so it was a easy to justify trade-up - half the money and a baler in better shape. I had a few problems with it beyond regular maintenance - the main one was that the input shaft snapped off where it enters the gearbox after about 55 bales. Lucky for me a fellow who came to pick up hay when it happened repaired the input shaft for me overnight for free! The plunger head wrist pin was worn oval, as were a couple other bushings. The needle lift pushrod broke off where it pins to the knotter shaft output disk, which was an easy fix. I machined and made up a new wrist pin which quieted things down significantly. I replaced the other bushings and broken pickup tines and consider the baler ready for the next 100,000 bales. I suppose if I had to buy new parts and have someone else work on it, I'd have quite a bit of $$ into it, in which case buying a newer baler may have made sense, but since I enjoy working on things and have a fairly well equipped shop, I can "afford" to pick up some great deals.
One thing to point out, I suppose - I checked the 24T out pretty carefully before buying it. There was no indication the input shaft was suspect. bearings and seals were all tight and it all ran fine. After taking it apart I realized someone else had been in there before me. There was evidence of a gear crunching event. The drive bevel gears were replaced at that time, so I suspect something broke years ago which jammed the gears and stressed the shaft. It snapped off through the pin hole cross-drilled through the shaft just in front of the gearbox used to secures a collar that locates the bearing into the gearbox. Inspection of the break indicated a crack had been progressing for a long time. I suppose my point is that old (or any equipment for that matter) may fail in various ways, some of which are obviously impending due to regular wear, lack of maintenance, fatigue, operator malfunction/error/abuse or cascade effects from another failure.
Try to find the least worn and best maintained baler you can - wear is evident in wrist pins (plunger connecting rod), PTO shaft/clutch/u-joints), bale chamber plunger guides, and knotters. Also look for cracks in and around the bale chamber, and the amount of rust in general. I've heard stories of 24Ts passing 1,000,000 bales, so they're obviously well designed and maintainable.