It's probably the pictures, but the leather and the 'silver' look like the quality you would find at a horse auction...i.e. Not worth $20 (let alone $50)
I would expect to pay $50 for a used reinsman bridle, or circle y bridle...do you know the maker??
Sorry to be the neighsayer - but you don't want to get taken!
It is good that the bridle fits and he wears it well, but quite honestly, most headstalls are going to adjust to fit your horse - - the big factor is the bit. (And if you can get the bit by itself and then attach it you your own bride...i think I would)
Just for comparison's sake, you can visit Horse.com and put together a new bridle (headstall+reins+bit) for around $50