I sold my almost complete collection in my 20s, because well, I wasn't at my smartest then. Drinking money and going out was more important. Kills me becuase I had what is now every difficult/expensive game to have.
Now in my 50s I've been trying to get the collection back and yeah, this is an expensive time to fire that up, but I've managed to scavenge everywhere and gotten a good jump on it.
That Stadium Mud Buggies auction is tempting. Gotten some good deals on ebay here and there, recently getting Body Slam CIB for only $70. Still a bunch of cash, but lower than some.
My best deals have come from Craig's List oddly enough. And I find being nice to fellow collectors tends to pay off too.