you can do up to 30 grafts per cm2, which is 1/3 density. you need two procedures to get really decent density, though 1/3 can stand on its own and look like thinning hair.
if you have a lot of area to cover, you will not be able to go that thick. all the really bald guys who look full in pictures actually left their crown empty and just did the front.
if you do FUE, it will be $5-7 per graft. For a strip procedure, $3-5 per graft. If you do a strip procedure, go to one of the 10 docs who do tri-closure, so you get a very fine scar. Dr Keene in Tucson is a great choice, as is Dr Ron Shapiro in Minesota. FUE is better for people with tight scalps, and will be invisible only if you scar well, which means you'd do well with the strip too. Going from NW3 to a good NW1 is probably 100 cm2. The whole male pattern baldness area of a NW6, above the NW2 line, is about 200 cm2.
The back and sides of your head can only donate 4000-8000 grafts, depending on your density. FUE can take them from more areas, but you will still look thin if they take a lot.
Your whole head has 100,000 hairs, and probably 40,000 FUs.