Ask HN: Marketplace for swapping

Do users want a marketplace which allows them to buy stuff/articles for a price (like existing marketplaces craigslist...) and by swapping articles that they don't want

Following is the use case for a swap marketplace:

1. User A searches for a something (say Article X) that he wants, and he finds that User B is ready to swap Article X.

2. User A finds User B’s list of “Wanted Stuff”, which includes a list of articles User B wants.

3. User A decides that User B wants Article Y, which has approximately same value (in $ price) as Article X that User A wants.

4. User A makes an offer to User B for Article X in exchange of Article Y.

5. User B seals the deal.

This marketplace allows transactions by exchange of articles and not just by price