alright, i am saving up for an autococker because i got to use a mech. cocker(i believe it was a psychoballistics one) and was hooked. i love the complexity of them

anyways, i am saving up to get one and i figured out ill have around $550 to spend at the end of july. well, i only have co2 tanks now so i will need to get them antisiphoned. here are my choices:
-ccm series 5 cocker... my only concern is how well the reg. handles co2
-wgp outkast... i like this one a lot, and i believe the stock reg handles co2 fairly well
-wgp 03 or 04 vert feed... a bit subpar compared to the other 2 guns previously mentioned, but i think i could pick one up for $300-350 and use the left over money to get a HPA tank.
-build my own from scratch... been totaling parts prices using ebay stores and things that have a buy it now icon(i hate being outbid) but i havent come up under $600. making sure i get ABSOLUTELY everything i need, any ideas for a full setup that i could build myself?
alright, those are the options im looking at now. i have a few general cocker questions also:
-what is the efficiency of a cocker? IE how many shots with a 68/4500, 88/4500, or 20oz co2 tank? would i be able to get a full case of paint shot through an 88ci tank with a stock 03/04 vert feed?
-can you suction time pretty much any cocker? or does that depend on the pnuematics and whatnot?
-with a $550 limit, what would YOU yourself get? i want to have as many options open as possible, but dont know where to start so i need some other ideas.
also, i have a 98custom now so i have most of the tools and oil and whatnot. i think i just need a valve tool, pnuematic lube, and maybe a few more things and ill be set.