I use eBay in conjunction with Aramex for shipping. Some sellers on eBay will ship direct to Qatar as well. You will need to decide if it's wiser to spend the extra on shipping or perhaps buy locally.

Aramex are a cost effective shipper from the states and the UK. When you join their Shop & Ship service they give you a postal address in the USA and UK. You have you items delivered to that address, and then they forward your goods to a depot here at reasonable rates.

I don't think selling items on eBay is a viable option from Qatar. But somebody else may think otherwise.