Affiliate Marketing Secrets

So my fiance and I were looking into starting an online business – probably some niche in electronics. But to the bottom line, I was wondering is it legal to post items on your own website and then have them shipped from somewhere else. Example: A customer visits my site and purchases an HDTV. I do not have an inventory – so when the customer makes the purchase can I order it from another company (Sam’s Club, Best Buy, etc..) and have it shipped to the customers address? My fiance says yes, but I don’t think it can be done that easily.. Any help would be greatly appreciated. Preferably someone with experience. Thanks in advance.