This might be a tough one. I was ready to say "no, it's not ripping them off" until I went and saw the listing.

In the title, you stated that the RRP was $49.95, so by buying it at $15.90 they're saving quite a lot. In some cases, though (and business-techies correct me if I'm wrong), the RRP may also mean the discounted price. For example, if an item in March 2012 cost $40 to buy but wasn't doing so well, it may get reduced down to $19.95 in September 2012. So, if that reduction is across the board and not just a special promotion, $19.95 becomes the current RRP. The question is whether the $14.95 that you bought it for was a special promotion (e.g. not the RRP) or was actually the revised and current RRP.

Maybe you could Google the specific item and see whether the $14.95 was just a special promotion or is actually the current RRP. An idea for the future may be to give an exact date of when it cost "$x.x" as the RRP, with a link or something. Or, as has been said, don't keep the original price tags on.