"It's basically unending on repairs, if you're striving for near perfection."
Supply and demand also plays a role.
"The steering sector's very important to check for wear and tightness," said Ed Bowman, a retired Tarkio, Mo., farmer. "Same for the transmission differential and rear end components, since the cost for gears, axle bearings and the like is awfully expensive.
"Also, rebuilding on some parts - such as to make bearing surfaces true and smooth - has to be done by an expert machinist," he said. "If something's not done right, vibration, breakage and other problems are sure to develop."
Resist the temptation to overlook major flaws in the sheet metal. Bud Panning, a Biggelo, Mo., restorer, says he prefers to start with tractors that have good sheet metal (or "tin work").
"It's hard to replace, so I look for it at sales, to use myself or sell," he said. "I also check to see if the motor's stuck, or if there's water in the oil. You can rock it by pushing a rear tire with the tractor in high gear, or pull the fan belt to see if the motor will turn."
Worn front ends can also run into a lot of money, he said. But many times, steering boxes can be built up and shimmed, and arms can be welded and ground back down, saving the expense of replacement parts. Use your own parts if possible, of course, if you can repair them. And always check for cracks along engine block lines.
"There are some things you don't have to worry about as much," Bud said. "For example, starters can be repaired fairly easily."
Nor should tire condition be considered an obstacle.