You see it all the time in eBay game listings. "RARE!!!" Of course, this being the internet, it's usually part of the full listing "GEARS OF WAR FOR XBOX 360 – RARE!!!" but occasionally, it's justified. Here we take a look at the different types of retro games and some of the crazy prices they're going for.

The popular desirables
These are the games that sold by the shedload in their day, so hardly count as 'rare' yet still seem to fetch a high price on eBay. Such as…

Final Fantasy VII - PC
Sure, everybody has got a copy of Final Fantasy VII for PSone or at least played it back in the day. While that version is still highly sought after (most likely by those who were too young to enjoy it at the time) with boxed copies going for £15-20 (about $35) on eBay, it's the PC version that's getting the biggest prices, as it's rarer. If you see it at a boot sale for a quid, pick it up for a possible 5600% profit.
Average eBay price: £57 ($114)

Secret of Mana – SNES
This seems to be a mainstay of second-hand game store cabinets at the moment. Always labelled at £59.99 (about $120), it sits there, just a bit too expensive to snatch up, goading us with its rarity. If you can find a version with the map still inside, you should be able to get that price on eBay without too much trouble. Is it any good though? Well, it's by Squaresoft – what do you think?
Average eBay price: £50 (about $100)

Super Mario 64
Everyone's got a copy of Mario 64 – usually a tatty cartridge with no box. You know, the one that was left in the console when you bought it second hand that looks like it's been used as a teething aid. But what about boxed copies? They're rarer, but there are still plenty around too. But unopened boxed copies? One just went on eBay for £166. That's over $300. Our advice? If you ever find one unopened, DON'T OPEN IT! You'll knock over £100 from its value in one fell swoop.
Average eBay price: Boxed, used: £15 ($30)

Above: Still sealed? Miyamoto would probably cry if he saw it, but a collector will be over the moon