Alex, I went into our www.MachineryPete.com Auction Price data and looked at JD 4520’s…I set aside the excellent condition originals, the rare FWA models and the super high end restoration job 4520’s. The past few years those high end auction prices on 4520’s run in the $21,000 - $64,050 range.
The Avg. Auction Price on the last (24) JD 4520’s sold in “Average/Fair” condition = $7,421 (High $12,000; Low $4,510).
My sense is the Kinze repower factor affecting value more kicks in when the tractor in good to excellent condition. On tractors in ok to less than ok condition - been sitting out for years, then I think main factor is that overall condition. So in this case I’d hang my hat value-wise on those last (24) average condition 4520’s sold = $7,421 (High $12K; Low $4,510).
Hope this info is helpful Alex. Good luck on getting the 4520 bought! Would be quite a cool tractor to own! Keep me posted.