Well now, let's get to business.
Are you going for CPU and GPU? If so, a single 360mm radiator is more than enough. If your case can't hold a single 360, either get the Dremel out, just buy a total of 360mm of radiators. I'd personally go for an Alphacool NexXxos Full Copper 360, which is at a great price over on Frozen CPU right now.
If you have your GPU and CPU in a loop, and the pump and res combined in one unit, either by a bay res with pump, or just a tube res, pump, and d-plug, then you will need 8 fittings; two per "unit". Go cheap; straight compression fittings. 1/2" tubing OD is pretty massive, and 1/2" ID is huge! I'd get 3/8" by 5/8" tubing if I were you, looking for a nice sized tubing, but still as large as you want. I prefer a thin wall, personally, so 3/8 by 5/8 is your best bet. Get 8x of these XSPC chrome compression fittings and a 10ft pack of this Primochill Advanced LRT 3/8 by 5/8, in whatever color you want.
As for coolant, I do recommend using distilled, di water, but if you reall, really want a coolant that is colored, I don't recommend going for anything thicker that Mayhems Pastel.
You want cheap, so I'll give you cheap. The CPU blocks all perform pretty close, but there are some clear winners; the Heatkiller CU 3.0 and the Kolance 380i are some of the best thermally performing blocks out there, but if you are on a budget, the XSPC Raystorm is where it's at. Everyone uses them, though; you might want a Koolance 370i, Mips Ice Force, or anything you can find used instead.
If you are putting your GPU in the loop, the blocks are so incredibly close that I get them to match my CPU block; Koolance CPU block? Koolance GPU block. EK CPU block? EK GPU block. In some cases, though, like mine, only one company, if any, makes a GPU block for your GPU, in my case, EK. If you have a reference PCB, though, you will have tons of options. You can always use a universal GPU block too, but I think they're pretty ugly.
Pump time. You have two real options; Laing DDC and D5 Vario. Both are pretty expensive, but if you get a small pump, you might not have that much expansion room in terms of flow. Still, a single MCP355 or 655 will handlo whatever the hell you throw at it, in 99% of cases. Quad 560mm rads, quad SLI, dual CPUs, would be fine, despite what a lot of people think, when they buy two, three, four, or in some cases, 6 D5s for their tiny loop. Wasting money for fun, really. I'm getting an MCP3355 with Petra's top for my loop, but if you can't afford the higher-end DDcs or D5s, much of any 12V pumps will do.
For the res, the size doesn't matter much. You can do a loop without a res, if you need to, it just makes bleeding really difficult. I'm a huge fan of Aqualis glass tube reservoirs, but they are generally massive and expensive. Bitspower Multi Z tubes come in lots of sizes, and aren't too expensive. Really anything will do. However, my favorite way of connecting the pump and res is with either a male-to-male header, or d-plug, so you save two fittings and tubing. Anyone will do; I'm a fan of Bitspower rotary d-plugs, but even an Alphacool male-to-male connector will do.
Need cheaper?