Scootrnerd: you are much braver than I. I have to left hands when it comes to things like drilling a tank....I am certain that I would generate a crack all the way down the tank. In that case the price is great, about 25% of a new one (at least 1/3 the price of new) and to have found one that is not used is a great find. Before you buy it look at the seams and make sure they are good and I personally would have them fill it while you are there to make sure it doesn't leak. If that all is good, you found a keeper.
What are you going to use it for? SPS, Softies???