I don't think it's particularly this company, it's most around Tottenham Court Road and the one's round the corner on Oxford Street.
They charge what they think they can get away with. Remember that most visitors to these shops are tourists, perhaps on a day trip. They are seen as fair game and gullible (is that the root of GULtronics?). Punter goes in shop, asks a price and is told some ludicrous figure plucked from nowhere. If he hesitates he may get told that they can do a better or special deal and the price goes down to twice rather than three times the real one.
If the punter bites that shop has made loads of money and most times the rip off is not realised until the poor purchaser has got home and it's not worthwhile going back, say, from Northumberland, to get recompense. The ones that do go back might get something done about it but even so, the shop always wins.
I work not far from there, I see it all - regularly!!
Cynical? Moi? Never!