Ask HN:Getting a client to pay for their site?

Three months ago I began a project for two guys(them US me China), who wanted a webapp.

I have no portfolio so they wouldn't make any down payment, fine I thought, and told them they can pay when it's done(stupid, slightly desperate me).

Everythings done except the style, it does everything they want and more(they seem genuinely happy with this).

Now they're taking ages to decide, I sent them logo's and templates to choose from (in their prefered choice of colour) a week ago and have heard nothing since.

This was to be done by the start of July, and the only reason it's not is because they're stalling.

I think because they haven't had to pay for it yet then they feel they have no reason to hurry.

It's only $3000, how can I get them to pay, or what are my options to monetise the site(ebay?) if they don't want to pay?