If you don't think there's a parallel in the market, then you aren't looking in the right way. And that's a bigger problem than just not coming up with a valuation.
I can imagine that the (particularly in the food business) there may not be another PRODUCT quite like yours but there's probably a parallel business model. Think about why people eat it, and under what circumstances. For example, is it a snack food? Then consider the business model of other snacks. Is it a meal eaten away from home? Consider other meals of similar price, speed and level of luxury. Is it a food gift item? An ingredient? a drink? Again consider how others like it are sold.
That will give you your business model, who your customers are what your price points and cost structure should be.