Always been a mystery to me how they price as well, never seen them advertise their prices, only ever got one in branch, but they are in principal a trade only supplier, In my region we've probably got 8 "shop's" we can access, but everyone one of them gives a different rate of discount, dependent on the spend we have with them individually.
They really don't cater for one off's, they want the trade accounts that regularly keep coming back, we, the trade, not the end customer, are then in a better position to get a deal and consequently get a greater profit margin, on the basis were on-selling with the profit margin they've given us by discounting from their retail price, which when you see them are extortionate, (last kitchen we got was retail @ £25K got it for less than £10K) if that makes sense, bottom line the trade get the benefit, the customer doesn't, unless you give it over.
PS I hate them with a passion, but have little choice but to use them by the fact they are well placed for easy collection and generally hold stock, a lot of kitchen alterations I do already have a Howdens one fitted, I'm doing a dishwasher install next week on a Howdens kitchen, need to take out a 1000 unit and replace with a 400 to get the DW in the 600 gap left, makes it easy to nip in and get what I need.