Anyone have a business set up on etsy or ebay?

[Firefly 35]

Just wanted to know what all would be involved in setting up an online buisiness.  From what I understand, shipping costs are one of the largest expenses, and the selling platform that you use (etsy, ebay, amazon, etc.) also takes a certain percentage of your sales.  Is this true, and if so, approximately how much does it add up to per month?

Basically, is e-commerce worth it?

[DailyDi]

I'm considering selling BiggerDiapers if you're interested in a turn-key start. Be glad to discuss the costs and such either way