I question whether the upright bell will make this more attractive -- especially since it's a removable bell with the Frankenbolts and such. For many people, the models with the integral forward-pointing bells are more desirable (and great for playing in jazz bands, Dixieland bands, or community bands outdoors!). I have a friend who has two vintage Kings, both 3-valve, one silver-plated, and in excellent condition. But he's put repair/restore money into each of them.
That aside, it's pretty dented up -- both in the bell and the main tubing in places. This is pretty straightforwardly fixable, but it does detract from immediate sale value. Likewise for the finish blemishes.
I think the typical buyer for this would be someone who would be happy to use it as-is (after cleaning it up, replacing felts, etc.) OR someone who would want to buy it and restore it, either for personal use or to resell. I'm skeptical that a flipper would be interested in it (in large part because of the needed dent/finish restoration coupled with the detachable bell and what you could eventually sell it for). Even if it were in pristine condition, I'm not sure that this model would be worth all that much (say $1,000 or more). But I could be wrong on both counts.
If I had this horn and wanted to sell it, I think I'd count myself lucky to get $800 for it.
You might contact Dan Schultz (http://thevillagetinker.com/) and ask him if he'd be interested in it or if he would give you more of a professional estimate of what it might fetch on the market.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)