There are a lot of controversy about it, I usually buy from my own Affiliate Links, never had a problem, principally when it is Clickbank products. Once, let's say you buy products from a warehouse, so you get a fat discount on the products you buy, let's say you want to buy something that your warehouse offer, would you buy it from a store or from the warehouse? I know it's a different example, but depending on the network, there is no problem, Amazon is aware of it and they do not give you commission if you buy from your own link.
Yeh it's easy to do when you're buying Clickbank products, but it's not always possible with other affiliate programs. Some really frown upon it, others make it impossible to do. Generally hosting companies won't let you do it. Just pay for it and spend your time figuring out how to make more cash Sean