This is the proverbial "No Brainer!" You start a business at NO COST to you!!
It's like an "online co-operative" where most of the Profit is shared among the members. My advice is to join and tell all your friends to join through you so they can also have a shop. They get some money back and you start to earn because of the Profit sharing!
So, instead of buying direct from those sites go via your shop and select the site you want to buy from. You pay the same price for your purchases, but because you've used your shop to access the retailer you'll receive a commission.
Just to be clear...NO sign up fee! NO monthly fee! And NO monthly qualifying purchase required either!
Only available for UK residents but very soon will be opening in the USA.