Im thinking about buying an diffrent system on ebay with a diffrent HDD would it work in the system?
you'd have to google your exact model ps3 and find out the model or part number of blu-ray drive and laser used in it then compare to the part used in the other ps3 .
sony used several different disc drives and you can't interchange the parts .
you'd be better off just buying a used ps3 that's in working order or buy a cheaper used 40 gig that you can swap parts with and then buying a larger hdd since an hdd is only going to cost from $40-$60 for a 250 or 500 gig
a good used 40 gig should cost about $150 so for about $200 you'd have a 500 gig ps3