Revenue or profit sharing can be a viable way to treat situations (like yours) where the capital amounts are fairly small. Generally the key is to balance the perceived risk with the projected reward -both the total ROI and how long it will take to get it.
There may be other options - depending upon your specific situation.
As I said previously, RISK (as perceived by the capital source) is the major influence on their expected return. One important factor in perceived risk is time. The longer one has to wait before one realizes their return - the greater the risk -both actual and perceived. When we structure deals of this sort, we usually "build in" some flexibility so that the return "adjusts" with time. Generally, this gives the capital provider a sense of "balance" between risk and return.
Send me a PM if you`d like to discuss your specific situation and scenario.