RDA rotors are a hell of a lot cheaper at trade price than they are at RRP, in some cases over 100%, though they do seem to give better trade prices to different entities.
A mate of mine picked up a set of slotted RDA rotors for $90 for his VR4 when he worked for a reasonably big chain in Sydney, but since he's moved to a smaller shop, the best he could get for me was $125 or so. I'd been quoted $300/pair retail from a few shops.
If you've got friends in the industry, shop around!