Alright, so I've basically done the same thing, I have a fullsize UK ISO Filco MJ2 and wanted beige/white cherry DS's.. the problem is that 99% of all the cherry keys you see for sale arn't UK or ISO and I couldn't really either afford to spend that much on another keyboard just to harvest the caps.
So what I did was basically trawl though the ebay listings for cheap sets and the 4sale threads on here and DT looking for parts. You're probably not going to find a full set unless your willing to spend alot, so my advice would be to look for German sets, and/or ANSI sets and try and build up your complete set from those incomplete ones.
You can do it for cheap if you bag together the keys you don't need into sets and sell them off.
I now have a full set of ISO keys, though my number and @~¬ keys are US/GER... unless you want to pay a lot, you kinda have to accept that its going to be a work in progress for some months and when I did that I actually really enjoyed it
mine when I had boosts RBG mods
and yeah I know you want a diff colour but the same principal applies