WHERE CAN I BUY LOWER BALL JOINTS FRONT OF CAR?

[WRS4]

I have an upcoming m.o.t due so just getting some small jobs that need doing on the car without having to rob a bank. I need the front lower ball joints replaced as there a bit of wear / play in the joints. Can anyone send me a link or point me in the right direction as to where to get these please.

Ive looked on ebay but some pictures look different to others so not actually sure what im buying? can i just point out if it helps anyone else that one of my rear brake calipers had seized and i purchased a TRW caliper off ebay and it was a perfect fit and works well.

So can i just buy ball joints? if so from where other than Audi of course as im not paying out that sort of money, or do i have to buy the lower arms too?

cheers