Bala - there is a very useful sticky regarding the use of 'aftermarket' wishbones and track/control arms at the link below. Not entirely sure if this is the same product or quality as those adtertised on eBay, however it clearly shows the importance to spend the extra $50 for a reputable manufacturer.
I am not a professional so don't take my word for it but I see a lot of guys going with TRW as an economy solution for those parts. That should be the minimum you should go with... unless of course there are other brands out there that I am not aware of.
See sticky here:
http://986forum.com/forums/general-discussions/20441-avoid-beware-ebay-seller-deutsche-parts-usa.html