While the ebay examples are tempting you have to remember that those prices are for original low mileage trucks that have withstood the test of time w/o aging, not restored ones. The rarity of being in like new condition with low mileage is what makes it desirable to collectors. Outside the collectible speculator willing to gamble on future values I think you are about 5-7yrs to late. Neither the current economy nor the economy going forward is going to support a price point of $6-8k for a 30yr old restored stock truck, not when you can buy clean trail ready DD's or 1st gen Tacoma's for the same price or less. I know people keep hoping the economy will turn around, but it is highly likely we are already in the economy of the future right now. We have been in a global economy since the late '80's early '90's, it is just now that we as a nation are having to accept wages that are globally competitive, the "home equity credit card" was our last ditch effort of trying to maintain living standards that are no longer viable in a global economy.
This is an interesting view point.
I've been toying with the idea of starting a company to sell restoration parts to the Toyota crowd. I might do restorations as project buildups and marketing, but not looking to make a profit on restoring them. My thinking is that these trucks are incredibly popular even 30yrs later, maybe more popular now then when new. Of course most of these folks just want to make a trail beater out of them, but a few I think would like to keep there's nice or restore one. Unlike other restored vehicles, these things drive really nice! You could easily daily drive one of these or take it on a long trip, plus the initial purchase price is fairly low all things considered. I think they are still too new to be considered "classics", but in time they will be, especially the first gens.