EKWB is one amongst many. XSPC, Koolance, Swiftech, etc...
Pretty much the goto supplier in NA: (FrozenCPU website is still up, but they aren't in operation last I checked, and still the case according to their front page)
http://www.performance-pcs.com/water-blocks-gpu?p=3
You still need a radiator, pump, reservoir, fittings, tubing, coolant (or water plus biocide/kills coil)
I chose to go full bore and did my CPU and two GPUs using a Swiftech H240-X (Pump, Reservoir, 280mm radiator all in one, plus a CPU block) Added two full cover GPU blocks and another radiator and I was off and running.
Lot of pump reservoir combos in there.
Start with this guide here, should be enough to get you started...