I've decided to first try patching it with Permatex, then then with Marine-Tex Gray if Permatex doesn't work, and then try tracking down a used tank in good condition and replacing it myself if patching doesn't work.

I picked it up from the shop yesterday and put the rear up on ramps in my driveway. It's no longer dripping, and the leak is apparently small and not obvious, so I can't see where exactly it is just yet. There are some leftover fuel spots, but there are no visible cracks or holes in the vicinity. In order to find exactly where the leak is, I'm planning on spraying the tank down with a hose and wiping down where the fuel spots were (to clear that area up), and then sitting the truck on level ground for a day with cardboard underneath to see if that gives me a better idea. If not, I might have to fill it halfway or all the way in order to see if that makes it start dripping visibly.

When I picked it up from the shop, he gave me a quote which listed about $136 for labor, $160 or so for the tank (there are some at junkyards within a few hours from me for much cheaper, but I'm not sure of the condition), and $50 or so for supplies, taxes, etc. Go figure.

elchatoloco - I very well might take you up on that tank if the patching doesn't work out. How would we know for sure that it's the right fit? Mine's a 95 fuel-injected standard cab shortbed, which is the only variant that they made in 95, if I'm not mistaken. I've seen it said that the tanks differ based on cab, bed, fi/carb, wheelbase, etc.