Most people spend some time looking around the shops, find the cheapest price and buy it there.
Yes, they've got the best deal 'seen', but with a bit of front and self-confidence, you can quite often get it cheaper by simply doing a bit of the old fashioned haggling.
Even if there's a shop which can say with confidence "You won't buy this at this price anywhere else cheaper", don't be put off - it's what you want to pay which will be the decider on a purchase or not.

Let's buy say, a £349 lawnmower

Have a friendly nature,not one which makes them feel you are just plain 'big shot' trying it on.

If they have a name badge on, say "Hello David........."

Say you're interested in the item and would like to give them your custom, you are keen to buy the particular product, but can't go to that price.

If they say they don't give discounts because it's at the discounted price already, tell them the price you are willing to pay as that's as much as you can afford.

If the answer comes back as 'No', ask to speak to the Manager or Supervisor.

If it hasn't (or has) the 'lowest discount' price, they may say they'll have a look at it. Maybe they will come out with the cost price, but bare in mind this could be that they brought 50 of them and got it below that price anyway!
After all, you are probably doing exactly the same as they did and bartered down a good price)

So, let's say they come back with a 10% discount taking it down to £314. You can then say the slightly cheeky "I was really looking for a number starting with '2'. I just can't go that far.

There's a strong probability they'll say £299. If so, say you'll go down the cash point and draw £275 thus saving them the paperwork and possible card costs.

All this may or may not work, but the main thing is IT COULD and OFTEN DOES!
I re-iterate the main thing is to be pleasant and polite - they are human beings and do having a living to keep up with the same as us.