Suggestions needed about Hosted or Self hosted shopping cart and action plan help.

Hello Warriors, first of all thanks for viewing this thread.
I have a question. Right now I have a few amazon affiliate site and I make about $100-$200 from them a month.
Recently, I have found a great supplier on handcrafted item niche and would like to open an ecommerce store. The niche I am getting into gets about 10,000.00 USA searches a month combined for about 13 keywords. (this is according to google).
Among them there are 3 keywords which gets majority of traffic. There are 5 players on this keyword. They rank top and they also have adwords set up on these keywords. I tried looking on adwords and Suggested bid is $0.80 for these keywords. Average sales on these keywords will be about $30.00. Margin is 100%. Means I can buy a product for $15.00 including shipping and sell it for $35.00 free shipping. Products dont weigh more than 2 lbs.
There are about 500 skus i would like to sell.
Also i am taking into consideration that I can sub-niche the niche and open 3 more ecommerce store.
I looked at shopify, bigcommerce, magentoGO ...non of them have a store Graphic layout that I want to use. Although I like the functionalities on all of them.
I was inclined to go with Magento go, but their storage limit is only 500mb for the plan i want to use. How many products can be listed with high quality images for 500 mb on an ecommerce store? Also as i have sales comming in and more customer information I have...isnt it going to consume data?
If i go with self hosted solution is VPS hosting enough for 3 ecommerce store?
I think that way i can save money.
Please provide some suggestion. I will ask more specific question when i get some answers.
Thanks and please forgive my English I have hard time expressing myself in English.