While I generally make my own sounds, I do buy sound banks form time to time. But I always look around for good sound banks at a good price. There are some really talented guys out there who make great patches and at very competitive rates.
40 or 50e is not something I'd be willing to pay. Then add a clump of VAT on top. I doubt they sell all that much to be honest.
It's a buyers market, if you're prepared to hunt the web.