do you have a normal job that you are trying to supplement your income with botting? or are you looking to live off botting?
if you are just trying to supplement your normal income then think about doing it this way:
start off with your normal PC, run maybe 2 or 3 maybe even 4 bots on it. so ya kicking in a little bit of start up cash. keep those bots going till they cover your costs and are at nil again. from there keep running them till you make $100 or so. with that $100 you can now buy some a 5th bot and another acct. remember you can get new cd keys for in game gold so it may work out cheaper for you.
but the main idea is expand your operation to as big as you want, but do it with the profits, so if all comes crashing down and you lose everything you can still walk away from it and say well i didnt lose any money out of my regular income, so im not better off, but im not running at a loss either. you are simply back at nil and have wasted a bunch of time. (depending on how efficient you make things).
i have no need for the money i make from botting so i started with 1 wow bot. i now have 3 wow bots and 2 d3 bots, i have had 3 wow accts banned and re-bought accts and 1 d3 acct banned and rebought that acct too. ive put a bunch of cash into my house deposit and im now building up another lump to expand again, my next goal is 8wow 4d3. thing is, i havent lost anything even with bans. but everything has been paid for with cash made from botting.
as for banning and IP tracking etc. shit anything could happen.
but i had 1 of my wow accts banned while 2 other ones were botting (the other 2 were on the same battle.net login too) and my 2 d3 bots were botting at the same time.. all from the same pc and ip. so if they did just ban everything associated to my ip/mac address then surely they would have hit my other bots too.
but as others have said. we dont actually have any clue about how blizzard does things, so its just a matter of giving it a shot and work with your own experience.