I have used QB for years in my job. Quickbooks pro 2000 allows emailing of invoices. I read about it, but do not use that feature. You can keep all your inventory, costs etc in quickbooks. I do not use it now for selling because I don't have time for ebay now, but the program I do use every day and it will do quite a bit and is well worth the money. You can even write letters now with MS Word and QB pro.
Allow yourself way more time than you think you will need at first because you will have to research how to do everything, but it really will be worth your time in the long run.
Good Luck.
It's not as easy as they want you to think, but it is a good program.