Choosing just one shop in london for a week-end trip

I went into TFG for the first time the other day. Got a nice t-shirt. Some good stuff but overpriced. Like most things though. I don't remember the last time I actually purchased a bike part from a shop and not online

I think one should remember that shops simply have to sell at the RRP, online shops however are generally selling things well below the RRP.
So yes compared to online prices all shops will seem expensive in general.