That stuff shows up at shows at very low prices. I sold some of the F9s with DCC decoders for 50 or 60 a couple of years ago. I would estimate 40-50 for the locos is very fair IF they do not have any broken gears. Sometimes these things have cracked gears on the axles. If that is the case, 10 is max. NWSL has replacement axles, but I think they are about 25-40 apiece, hence you are back to 50 to get it running.
If the cabooses and stock car are all OK, no broken stirrups or other broken parts, 20 max. Since you are offering for whole batch, I would say 15 apiece.
The wooden partially built kits are very subjective. If you think the workmanship is good, and the rest of the parts are there, and you feel like like it, 20. Usually when I see partially built pieces, the workmanship is bad or they have have been badly shopworn and are not worth much more than 5.
Un built kits sell for anywhere from 10-25 at shows depending how badly the guy wants to sell and the buyer wants the kit. They are usually specific prototypes and build up nicely if it fits what you are modeling. Definitely a supply and demand situation. If you have little interest, they are not worth much to you and vice versa. Remember the typical old kits usually came without trucks and couplers, so you have to buy them. some of use often bought trucks and coupelrs when we bought the kit and put them in the box. You could check.