Hmmm... sometimes small dings can be fixed, believe it or not, using a good toilet plunger (I have not personally tried this, but supposedly if you get a good seal with enough suction, you can actually suck out the dings). However, this technique usually works better for doors and other side panels, where a thinner layer of metal (or fiberglass) is used than the hood, which is often made of thicker, heavier materials. I say try the toilet plunger idea (you need to wet the suction cup to help get a good seal), but I have a feeling that your hood may have too much integrity for this level of force to be sufficient to pull out the dings. I dunno, give it a shot.
As for the magnetic detailing, I've never heard of that. But if it works, more power to you. I suspect that you may be stuck just accepting the dinks as imperfections in an otherwise beautiful Honda, having to use bondo to just fill in the dents and have the surface area repainted, or replacing the hood - not attractive, as I would guess this is a $400 to $500 part.
As for the pricing, I need to remember that when I was looking at Preludes as the price I mentioned as being what I though was good, that was in the fall of 1999. So projected out, I guess $14,000, especially given the fact that the car has blemishes, seems like a pretty good price to me. You might be able to do better, but not too much.
I am sure you already know of strategies to use when shopping for a used car, but if you need suggestions, let me know. There a few trouble spots I wish I'd looked into before taking my Integra home. I still would have gotten it, but I would have worked the price down a little more for the things that I needed to repair for it to be in tip-top shape.
Good luck, and I hope you enjoy your Prelude!!