Might lose some people, but if all 3500 stay, you only need each person to pay .015 per month. Of course this is just hypothetical. Maybe its $1/month.
because of the early stage of your product without proven cash flows, it might be helpful to look at comparable transactions in your space or how the buyer (or its competitors) have bought other similar companies like yours. You might even want to look into hiring an investment banker that has represented companies like yours that have sold to larger companies, since they will probably have most relevant valuation figures.
Lastly, cash is king. Try to always get as much cash as you want, unless it is a really stable stock, i.e. Google/Apple.
In the end, get good counsel and it should be a market pricing sort of deal.