I think JuliaKM is stuck and can't get the thing to work completely though and ended up using e-commerce. I think it's more for paying to publish content...which will work for things like if a user want to submit listings, articles or images, then they will have to pay before it is published. I don't think they necessarily need to pay first - then create, but they can create first and then go pay. Once payment is received, then it's marked to be published/approved by admin (admin will receive a payment notice). Create first then pay will need a notice on each type of node creation page that tells the users they needs to pay before the content will get published though...

I guess this is different since it creating content/product to be sold...