I'm a former classic car appraiser and have bought and sold four Studebakers over the last several years- a '54 Conestoga, a '62 GT Hawk, a '57 Silver Hawk, and the '63 R1 Avanti (R4223) I still own. When putting one up for sale, I always try to read the market and price it at roughly 110% of what I expect it to sell for. A much more realistic approach than the pricing I see on many cars listed. I don't use the spaghetti at the wall approach. So far, every car I've listed has sold within a few weeks.
Not currently considering selling it, but if at some point I were to sell the Avanti, I would price it between 25 and 30K. This is based on observing the market over the last year or so. The car has an inch thick book of receipts from the previous owner for mechanical repairs, including a thorough engine and transmission rebuild. It has automatic, PS and TT. I've repainted it in Avanti Gold , updated the A/C to a modern system and installed a Turner brake update. Original wheels and hubcaps are in storage. Had I not done much of the work myself, I would probably have 50K in it. I'm probably giving away my labor, but that's OK as that is the part I enjoy.