1. You can telephone them to get prices.
2. I believe they will often price match many things - get yourself the Red Laser iPhone app and you can easily find the best deal by scanning the barcode in store.
3. Make sure you have a BAA worldpoints card - I think there may be a sign up bonus somewhere
4. There may also be a current promo for bonus worldpoints if you spend a certain amount at Dixons
5. I have found Dixons T5 very competitive in the past, especially for Apple kit. Of course you can probably buy cheaper online but there's the benefit of getting what you need there and then, tangibly, and that is certainly worth a few pounds over and above the very cheapest deal out there.
www.baaworldpoints.com