None of these replies actually address the question.

You should make the exchange a secondary feature while focusing on developing a cause for people to exchange - that is the only way for you to survive.

Use the 25k to develop an MVP, seek out long term incubators and advisors.

Pay a research firm to dig into your features and use the result to create a stronger point for your exchange to exist. Focus on giving a service to the people beyond being just an exchange, because there are many 'just exchanges' out there that aren't 'making it' .. if you know what I mean.

Need more advice? My inbox's doors are open to you.