eBay - Any way of properly judging the quality of spare parts?

[WorldClassAccident]

I am looking at the front control arm and there are wildly varying prices. The first few examples I found:

£63 for the control arms
http://www.ebay.co.uk/itm/BMW-E36-FR...4AAOxy4YdTXYfx

£72 for the control arms and ARB link
http://www.ebay.co.uk/itm/BMW-Z3-1-9...KWVt7lUeyYRDog

£73 for the control arms and ARB link and tie rods
https://www.ebay.co.uk/itm/Repair-ki...YAAOSwax5Y1o-x

£108 for the control arms and ARB link and tie rods
https://www.ebay.co.uk/itm/FRONT-SUS...4AAOSwhkRWgi8P

I appreciate these are not genuine BMW units but do I just buy the cheapest I can find?
Are there any trusted brands in the spares market I should look for?

I don't want to spend somewhere between £70-£140 just to find the parts are made from cheese and don't fit. At the same time I don't want to spend £££££ just to buy from someone with a nicer website.

Help!