Just got a pack of key caps from wasdkeyboards and I thought I'd post a pic comparing the red tone with the red key cap that came packed free with leopolds from elitekeyboards (I didn't see an existing thread on this).
The center is the free red key cap from EK; it's flanked by two red caps from wasdkeyboards. (Pardon the dust.)
http://imgur.com/xK2ciAll other key caps in the picture are stock from the FC200RC/ABN.
The EK red cap is a substantially deeper red, whereas the wasd version has a slightly orange cast. For best viewing, stand a little back from the monitor; up close your eyes will average the red tones together. In person the difference is even more dramatic. They both look good, but you won't really be able to mix and match them side by side unless you want the color difference.
I'm not too surprised. Color matching for industrial products is hard. Still I thought this might be useful information for newbies, especially as in the US I expect many will get their start by ordering from EK and then adding some caps from wasd.
Hope this helps.