
The site is running the C.R.E. Loaded web shop, which is written in PHP. The speed of the page is acceptable, as is the design (although I did see a few cosmetic problems running FireFox).
A quick price check on 1 Day Acuvue first shows that it's impossible to order only one box - minimum are two boxes. GreatShade's price, including UK delivery, is 40.54 GBP (vs. VisionDirect.co.uk at 39 GBP including UK delivery), so the prices are competitive, although VisionDirect.co.uk beat them on all the half dozen or so products I checked.
In any case, they would be interesting to check out if VisionDirect.co.uk didn't exist but, in the meantime, I suggest you stay with the best ;->