I've seen claims made on eBay auctions for these reflectors claiming they'll reflect up to 80% from back of fireplaces into the rooms making your fireplace more efficient.

Can they really save heating fuel?
The 80% claim was for a mirror polished stainless steel heat reflector.... "as good as your bathroom mirror" finish. Can a mirror reflect up to 80%?
Will a mirror withstand the heat of the fire?

The short answer, is the best way to make a fireplace efficient is to install a "Heatilater-style" of fireplace with a blower. Otherwise you're heating dollars are flying out the chimney. Don't think something like a reflector will save you money. That is of course unless you plan to burn your fireplace anyway...

Then the reflectors will let you fly less dollars out the chimney...

I am wanting to buy a fireback, but I found a product called firebrite reflector. It is stainless steel and 3 sided and says it will throw out 80% more heat than without a fireback. I cant find any info on this product when it comes to reviews or anything. Does anybody have any experience with either one? I really want something to make more heat come out of the fireplace without buying an insert or grate heater due to their price.

A fireback is basically a piece of metal that reflects the heat into the rooom instead of letting the bricks in the fireplace absorb it, or letting it escape into the chimney. It sounds liek your firebrite reflector is just another fireback with a different design. Most firebacks are dark colored because the soot and smoke make them that way anyway. Your firebrite reflector may not stay shiny, you said it was stainless, so may not work much better in the long run anyway, unless you plan on cleaning it regularly. My fireback works fine, it reflects heat into the room and is worth the money.