I think you should definitely reach out to those startups to see if they'd be interested to buy it. Maybe you could package it more as a software consultancy service where you'd customize the code to fit their needs. Since lots of startups already been using software house to bootstrap, I don't see why they wouldn't be interested in your code.

Having said that, I don't think this would be easy feat though, especially considering you've spent 2 years building it, the price might not be something affordable for early-stage startups.