Which e Commerce Platform Should I Use?

As everyone suggested. You should go with Magento

First off, I would only create one eComm store per business. Use the additional URL's as splash sites with unique content regarding that particular product... My experience since June has been that stores targeting 100's/1000's of phrases are ranking WAY better and easier. Basically, it's easier to rank an authoritative store for "redbaseballbats" than a 2.0 or splash site. Also, with the money you save you can buy a user friendly platform like Magento or Volusion which is worth it's weight in gold when managing sales, fulfilling orders, filling for taxes ETC...

Just my 2 cents.