What are you trying to buy?
Almost every market place has been suggested by OmegaStarScream and if there as some goods or products that you are looking for.
Here in forum you can also look for some various items that you can straight pay with bitcoin from the merchants / sellers by those products or services.
Goods section that has other child boards
Computer Hardware ,
Digital Goods &
Collectibles.
actually i dont try to buy any goods, i just want to know how the marketplace company run a bitcoin payment method.
thank you for the source, i will learn more in bitcointalk marketplace forum.