I've spent a huge amount of time installing, testing, uninstalling, testing and going round and round looking for an eCommerce site the suits my needs perfectly.
Prestashop is absolutely magnificent. The authors of this product know exactly what is required to run a complex shop with a multitude of combinations of attributes that have specific prices per product. I haven't come across any other platform that has this feature as a module, let alone built in. It also offers multiple shops in one platform which is great. i am in the process of rebuilding 3 eCommerce sites which are a real pain if I have to do it online. I simply installed a local copy on my laptop and I am now in the process of setting the first shop up. It took me about a day to come to grips with the platform and I find it to be extremely intuitive one I worked out how it works, where all the configuration options live and how to use them.
Tomorrow will be spent doing artwork for the shop and loading up 350 products with a total of 14 combination per product. Once this lot is uploadd and running on the site further combinations will be added that will exponentially enlarge the product offering.