Well lots of people mix and match parts.
In general there are a lot of things you can buy in a lot of price brackets.
Some popular pumps are
Via Aqua 1300
Eheim
Danner Mag 3
Maxijet
Just to name a few. In my system I use the Maxijext 1200, because it is small and has thus far been reliable to me. A lot of people choose Eheim or Danner though. I think my pump is 295gph or so, its been a while since I needed to recall the specs.
There are more expensive pumps out there as well, such as Iwaki, the pumps sold at Dtek Customs, Danger Den, and Swiftech pumps.
Alot of these pumps hover around 300gph, give or take, depending on model.
For a CPU waterblock, a lot of people choose to be real spending and purchase things, like the WW (white water) which is at the top end of the performance spectrum. There are also others available from other companies I believe. I honestly haven't purchased a W/B in a long time now.
I use a Danger Den Maze4 myself. Its prices at a slightly less than $50, respectable cost, and seems to get the job done great, depending on your needs. There really are tons of blocks out there though, asking a more up-to-date W/C'er will get you some good answers.
For a radiator, I use a Dtek Pro Core. Which is a heatercore, one of the best radiators you can use in a system. There are plenty of heater cores for sale on the net, or in auto shops as well, buy they may require more effort than the Dtek core. You can order it painted if you like, and choose your hose barb size, etc.. I use a Dtek fan shroud with the core, and run a 120mm Enermax fan (adjustable to control noise).
I also have a custom built reservoir. You can build one yourself with a trip to home depot, using a 4x4x4 PVC box, usually found in the electrical section. They come with a lid and o-ring type seal.
Some people with room like reservoirs because they made it easier to fill and bleed the system, while others with less room, or fear of a leaky reservoir prefer a T-line. This is basically made using a T adapter in the W/C loop somewhere, and and consists of the T, and some extra hose that can be capped off. You fill the water in through that hose. Sometimes it can be a pain in the ***. Its all up to personal taste though, and imho if you do it right, a reservoir can be both stylish, and leak-free.
Thats a rough idea of a basic no frills system. Hope it helps you out.