How to make money as an online service broker?

Hey guys, I've got a money making project in mind that I'd like to share and discuss with you before running a test. There are many freelancers on specific platforms like Elance trying to make money selling their services. Hire them for your own clients. Pay freelancers whatever they want and charge your clients a lot more. The difference is yours. You are the middleman.

Let's get to your work flow as a middleman. First of all you need a service that's in high demand. You might suggest logo creation. But you need repeated customers and high order value. People usually buy one logo once they start a new business. Nobody gets tons of logos on the regular basis. So if you go with digital drawing services for instance, your client might want to order 100 images today and 1000 next month.

However, here's a problem. You pay a freelancer your own money. For example they charge you $10 per digital illustration drawn and you charge your customer $50 per item, keeping $40 profit. What if your customers order 1000 images from you right now? You will have to pay out $10,000 to freelancers for their hard work. Not everyone has so much money to invest. There seems to be no way to use $50k collected from your customers to pay freelancers because it takes too much time (a week/a month) before you get hold of this cash. Too bad Paypal does not allow to receive funds in some countries. Any ideas?

Also, when it comes to marketing and advertising, you risk to waste your own money. I think building relationships with business owners who might need your services using social media would work just fine. You will not find a lot of customers this way of course. But if one customer spends at least $1000 per month buying your services, it's awesome. Here comes another challenge for you. You've got to know who spends $1000 per month on the internet and what they buy before you pick up a product or service to offer. Please, share your ideas.