It's true that there are a lot of the Olds Ambassadors out there. SOME of them are in good condition and playable. But many have been "used, abused, and put up wet" (as my wife has described some old horses). Many were used as school instruments and not maintained well. This often included the failure to oil the valves on anything approaching a normal schedule. So beware of serious valve leaks in any horns of that vintage.
In full disclosure: Some years ago I bought via Ebay a Martin baritone virtually identical to these Olds horns. 3-valve, removable bell. The finish was worn, as I could see in the picture, but it wasn't dented much. I knew it would require some rehabilitation and was planning on doing that. Alas, when I got it, it was quickly clear that the valves were shot. If you put vasoline on them you could pretty much play a scale a few times. Otherwise not. Rebuilding the valves would have cost me more than the horn was worth and more than I could likely find another used horn that was actually playable. Since I bought it as a "project" horn, I regarded it as no great loss and ultimately donated it as a wall hanger to a local elementary school.
You can indeed get some of the old horns in good condition that are playable and inexpensive. But how do you tell? And then what do you do if it won't play and you're told that a valve restoration will cost you $500+. Just a thought and a caution.
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)