Nice find but pretty expensive
If there's enough material to produce 1000 tubes which you could sell for $25 each you could get $25,000 back. Then you'd still have to produce another 600 tubes to break even but you don't have the source materials for that so it will cost you extra money. I doubt there are enough people on this planet interested in nixie tubes to sell something like 2,500 pcs. That's 100 factory boxes for $625 each!
I bet you might be able to sell 1,000 new in-18 but I wouldn't think you could sell them for more then $10 each... even at $10 each, that's a gamble . How long would they last? How many problems they might have?
... I don't think you could ever make money on it.. think of all the costs, and then finding a whole sale dealer to buy them from you...
It's a cool idea to start making nixies again, but there is a reason why nobody makes them... they are too expensive, and to small a market.