Those prices ($18,500 ea.) for a Tiger might not be too bad. I'd have to know how much rust there is on the one that is stated to have it. I've heard/seen a few Tigers going in the $120,000 range. But I believe a lot of that was alcohol and auction driven. I still think you can get a decent one for under $50,000 if you are patent and not expecting pristine. $60,000-$80,00 would be more typical for very nice Tigers. Thus the $20,000 range for Tiger than need extensive work.
I got mine in 2000. A basket case for sure, but not the worse kind. It came with $800 in new parts, a complete front clip and the hard top. The asking price for everything was $5,900 and I got it down to $5,100. I got the Tiger itself for $3,500 and the parts, clip and HT were valued at the remaining $1,600. These items, not installed, were thus not taxed on the sale price. My only problem is I stopped working on it in 2004 and it still sits. Three other cars got in the way (my Turbo Pinto being one of them) and now my daughter's 6 month Tiny House project is now entering its third year of construction.
My apology to the OP for the diversion. But when a post gets 7 pages long..., they tend to meander.