Finding a large software player in that market (or a similar one) is a good way to find a buyer.
-Find out who sells the big management systems. They often have projects that may extend into your market. It's cheaper for a big company to buy existing code that can be rebranded than to start from scratch, especially if you're willing to be flexible.
-Find consulting shops that work in that space with larger hotel chains. They might be able to sell this in and give you a success fee.
-Find a "founder" with sales/marketing experience willing to take this on as a real project. Lots of non-technical people in the space have connections, but no capital/product. You're basically bootstrapping their company with technology investment.
-See if there are 'resellers' or marketing reps that sell similar systems in the space. They might be willing to help you find a company that can market & support the product for you.
-Be flexible on how you get paid. For example, provide the code to market for 24 months for a percentage of gross sales. That would mitigate the buyer's risk, while still providing you with upside potential.
My experience in buying sites is that without customers, it's basically a huge risk, so prices are very low.