I got my D&D Basic box set from a charity shop, £2.50. There’s one going for over £150 on ebay right now. Got my Baldur’s Gate box set from a charity shop too for £2.50. I also got Flash 4 (I think) for a couple of quid, it was selling second hand on amazon for about £200, but I was an anxious, clueless kid and was too scared to sell it.