I don't know exactly how many items I want to sell and I might change my mind. No problem! It is expected that you will want to change your online store around. It makes it more interesting for visitors. If you ever had dreams of having your own store, it is just so much easier and less expensive to do it online. And for that matter, you can try out many ideas online without a major impact even if they turn out to be "duds". If you tried that in "real" life, you would have major financial problems.