DSF

I want to buy some round cornered rectangular metal keyrings.

On various sites they all look the same but the prices vary, would they all be exactly the same thing, in which case I may aswell buy the cheapest.

Nope they are not all the same trust me. Cheapest ones we find have rubbish boxes and metal inserts don't fit snug so you can get minor gaps. We use Xpres (although boxes do come with stickers on that don't peel off) but use to use BMS until their boxes went from black to stripy grey (which our clients hate).