Can the Resource Manager be used for a gallery/blog/store/etc?
The primary function is for managing resources but it may be possible to adapt it for other uses. Editing phrases and templates and additional third party development may be required.
Xenforo Resource Manager is used on here for people to share resources and for some to sell them too, though of course they use additional services for the selling part.
I think you need to be more specific about what you require from a "marketplace" add-on for folk to be able to give you suitable recommendations or to say if there isn't anything available to meet your needs.
I wanted a subforum and category at my site imlightning.com that says Marketplace and I wanted to have pictures of ebooks or videos on one page with links to more info. That would be for my products and for others who want to sell at my site (via a fee $10 or whatever). That is the basic idea.