An interesting auction has popped up on "Chase the Chuck Wagon" in the form a self proclaimed "rare" variant of the Mega Man 1 cartridge containing five screws rather than the standard three holding the cartridge together. Make of this what you will:
"What you see is what you get. Rumored to exist for years, finally uncovered last year by myself, and recently confirmed as a legitimate variant when another was discovered in the wild by user "hybrid" at www.NintendoAGE.com. I've compared the back-labels and internals with hybrid's, and the chips are a date-match: they're brothers, and neither is a fake."
As of this writing, bidding is currently at $81.11 with thirteen bids. Wow. All this for two extra screws? That's hardcore.