Hey Birilli! If you haven't already found what you're looking for:
If you're trying to build your own Tri-Cree on the same star pads as The Custom Saber Shop and other finished component suppliers, you'll be looking for a SinkPad-II 1938c. Unfortunately, the only way I can find them for sale is 2 panel sheets (minimum order) of stars = 30 pieces (stars) = $100 from SinkPad.com which is now AduraLED.com. So, the good news is that translates to $3.30 per star. Bad news is that if you have no need of the other 29 stars, you're stuck with $96.70 of product. Therefor, you'll have essentially paid $100 for one SinkPad-II. Plus a few dollars a piece for the CREE XP-E2's from Digikey.com or Mouser.com.
OR, you could spend $27.50 from TCCS... http://www.thecustomsabershop.com/Custom-Tri-Cree-LED-with-modified-base-P1139.aspx
Or, contact SaberBay on Etsy
$24.00 - $34.00
Or, if you're in England/Europe, contact Etsy :: Your place to buy and sell all things handmade
$22.19 - $25.35
As far as "which white is best for FoC", that depends entirely on the way YOU want it to look. There are warmer, more yellowish whites, white whites, and more blueish whites. Each will effect your main blade color differently. If you go the $100 route for the stars, all you have to do is order up at least one of each type of white, 3 of your preferred green, and 3 of your preferred red, and experiment by creating 3 different Tri-CREE stars (out of your 29 'spares' ;) ) and see which one you like the FoC best in and use that one in your saber!
I know what it's like to want to build every component yourself, sort of a "Your skills are complete" kind of thing, where you can say you made it all yourself. But then you start adding up the cost of all of the tools, machines, powersupplies, etc., and it's quite daunting!
Good Luck in your build!