rear disk brakes, what options??

[bug-er]

hey guys
straight to the point, what options do i have in the way of a rear disk brake setup??? i know that there are kits that you can buy, but your talking about £500, and i think when the time comes to replace the pads and discs i'll struggle. Ive been reading up on the early porsche 944 turbo full disk setup, being as just the rear porsche disks and standard front disks shall give too much rear bias, is this true??? can this set-up be used with a swing-axle gearbox?? are these the calipers with the porsche cast into them??
Is there a setup off a modern production car that i could use??? Im really looking to spend no more that about £350, what can you guys suggest??? ive got access to most machining stuff, and have a good mechanical knowledge, so would be quite capable to do most things.
I know alot of you guys have covered most conversions, so would be really appreciative of some help
Adam