There isn't really a full beginning to end guide that I know of, bass' guide here is a good starting point https://www.overclock.net/t/1087013/start-subzero-cooling-for-under-200
, there are a few other threads for new sub-zero coolers question & answer.
Price really depends on a lot of things, read bass' guide first & you will have a better idea. Top of the line hardware isn't needed (unless going for overall world records), although a good motherboard does make subzero easier.
If done right all components should be reusable afterwards, but for first time freezing cheap hardware is nice, if you do have a mishap, less money out of pocket.
Currently the 3570k/3770k is the weapon of choice for intel & ln2 (3770k tends to be better bin). They do have different max frequencies, finding a great chip isn't easy. Pretty much all processors are good to freeze, except the sandy bridge & sandy extreme chips, they just don't really like the cold.
Chips with an unlocked multi are better/easier for max frequencies.
Don't forget AMD, they don't score as high in benchies, but can be more fun to freeze than intel & are great for frequency validations. Most don't have coldbugs/boot bugs the way many intel do either.