pens:
[0] Pilot Razer Point (Black, very fine point)
[1] Uni-Ball Stick Micro Point (Blue, ball-point but with fluid ink)
[2] BIC Cristal Ballpoint (Black, extremely cheap)
Paper:
[3] TOPS The Legal Pad (white, standard us size, wide ruled)
[4] Staedtler Engineers Notepaper (lightly gridded)
[5] Moleskine Notebooks (Large size, hardcover, gridlines)
[0] - http://www.amazon.com/Pilot-Razor-Point-Marker-Stick/dp/B000...[1] - http://www.amazon.com/uni-ball-Stick-Micro-Roller-60151/dp/B...
[2] - http://www.amazon.com/BIC-Cristal-Ballpoint-Pen-Medium/dp/B0...
[3] - http://www.amazon.com/Legal-Inches-Perforated-White-Sheets/d...
[4] - http://www.amazon.com/Staedtler-Translucent-Bond-Pads-100/dp...
[5] - http://www.amazon.com/Moleskine-Classic-Notebook-Squared-Not...
Pens are all different: there are good gel pens (Sakura Gelly Roll, Pilot G2), good fountain pens (Lamy Safari, many many more), good art pens (Sakura Pigma Micron), good fine-point pens (Pentel Slicci, Uniball Signo Bit), and even good ballpoint pens (I like Skilcraft retractables, plus that 4-color Zebra pen). Some will bleed through on thin paper (especially fountain pens), so you lose 1/2 your notebook capacity. Not all pens/inks are waterproof (!).
I like pencil and Muji pens, the ones that are about £5 for a 6 pack.
Notebooks: Rhodia, Clairefontaine, Leuchtturm1917, or equivalent quality. Should be around $15 depending on size. Moleskines are no-go (ink bleeds through page)
Ink: Private Reserve is a nice starting point. I am particularly fond of their foam green. $11 for a 66ml bottle.
Shop: I really like Goulet Pens. Good service, amazingly careful packaging.
Source: personal experience and preference.
Source: I have $100+ pens but I'm using a Metropolitan literally right now.
Edit: after reading some reviews the Metropolitan is now on my buy list. Thanks for the tip.
Yes, pencil does smear a bit, and those non-mechanical pencils get annoyingly short. But pencil is surprisingly durable (against light, and even against water accidents).
And cheap is a big psychological factor in "I want a set of those everywhere".
Gel pens tend to smear a bit too much for my taste and run out of ink more quickly than I'd like. The rollerball pens often feel a bit too scratchy on the paper.
Most traditional ball points of any quality retract their point by clicking. I find that this is great for carrying a pen around in one's pocket, but the ball point tip invariably has a slight amount of play since it is not attached to the pen but simply passes though an opening in the outer cylinder of the pen.
I notice this troublesome movement at the tip the most when doing complex mathematics. Once I'm working with small subscripts I want the pen's tip to start writing at precisely the location that I've placed it on the paper. For this reason I recommend a ball point with a cap where the tip is actually affixed in position and doesn't retract. The Pentel R.S.V.P line has pens like this and they work very well for me. The pen is comfortable to hold, having a wider barrel than many cheap pens and incorporates a elastomeric sleeve where one's fingers grip it. The barrel is a good length to it works well with or without the cap. The "fine" size make nice thin lines, the tip is of higher quality than many other ballpoints I've tried and doesn't skip for me at all, nor does it collect a little ball of gooey ink that will be deposited on the paper at the most inappropriate place.
In addition to being reasonably priced the Pentel R.S.V.P line can be found everywhere, Office Depot, college bookstores, and even the supermarket. The pens are also available in a range of colors, two line weights, and even variations like short ones (intended to be carried in a small pocket) or ones that click to retract the tip (but see my comments above).
My favorite ink color is purple. I generally got very good grades in grad school and I was thinking one day while fishing out my paper from a stack of graded papers that it would be easier to find if I turned in my homework on a off-white or pale yellow paper. I started doing this and then adopted the convention of doing my work and tests in purple ink as well. My thinking was that the overworked graders would learn that my work on homework and tests in purple ink was almost always correct, and I believed that sometimes I got the benefit of the doubt when they had to interpret a weaker answer of mine because of the purple ink. For business use I revert back to blue-black ink.
As for paper, I really like Japanese notebooks. The paper is of high quality, and I like the narrower aspect ratio of ISO notebooks because it fits easier into a backpack.