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.

I solve all that with one word: Original. 😉

i.e. Original RRP $49.95

I've had people pay over the original RRP both for new items and even secondhand (at auction, where the prices were started lower), but as has been suggested, I remove markdowns if I can (they're generally not what I've paid for an item, anyway). 

Sounds like the buyer's going to revise the feedback, though, so hopefully it'll be resolved soon.