Wherever you get them from, things to watch out for are:
Puma wingtops are a different size and shape to older defenders. They might look the same, but when you put them side by side there is a clear difference. So make sure you order them for the right vehicle or they won't fit.
Also, decide whether you want 2mm or 3mm plate. The 2mm will be cheaper, and i found them fine for the seals, but for wing tops and bonnet you might want to go for the 3mm in case you put weight on them one day.
Also, some makes will be predrilled, which saves you time and messing around to get the mounting holes symmetrical.
I did also find that the wingtop rolls weren't quite the right amount of roll. But the neoprene gasket helps quite a bit to make it look ok.
Screwfix is a good place to get a bag of the countersunk hex bolts and washers and nuts. They are m8 if memory serves.