Machine Polisher? You won't get much for £50 unfortunately. Try £150. The DAS-6 Pro is a good starter and it's what I have. Have a look on Cleanyourcar website, you can get a few different kits on there ranging from £140-£180.
I've learnt the lesson on buying cheap pads and cheap polish and then wonder why pads are breaking up on me and not doing any polishing atall.
The best i have found and i use is Koch Chemie pads and polishes (proper stuff and works a treat!!!)