As you see, it's hard to get a clear, solid answer to this unless someone on the site happens to have bought or sold the identical item recently, and even then it depends strongly on condition and how you try to sell. As noted above, the receiver is probably worth some money, maybe $200-300 in good condition, the rest not so much - perhaps $25 for the CD player, and maybe $50-60 for the speakers. The website hifishark.com lets you enter any audio product and gives you a list of current and recent ads for that piece. But keep in mind you'll be seeing mostly asking prices.