Here you can find piles of rubbish but if you an expert in antiques you can find something valuable on a decent price. They sell everything there, nazi staff, Russian staff from the communist times, Bulgarian medals, daggers, etc. from the WWI and WWII period. Of course, they will swear that whatever they sell is authentic but you never know 
And, of course, whenever they see a foreigner they try to rip him off. No need to worry for communication problems if you are alone, they speak foreign languages to some extend, only you will have to pay a higher price. So, it is a good idea to have a Bulgarian with you to help you negotiating the price. Anyway, the place has its own athmosphere and I find it amusing to walk around from time to time.