I'm in no position to advise on the cost of a Tinder-like app - having never used it myself.

I can however share some thoughts on Freemium.

Freemium is too often engaged because it is easy - not because it is right for the business. You'll still need to determine how'll you make money, even with freemium, so it isn't an escape hatch from figuring out monetization - knowing how you'll make money from the beginning is critical.

Check out this video by Dan Martell: http://www.danmartell.com/4rulestofreemium/

I'll summarize the decision points around freemium below:
1. There are 10M+ users in your market. 2. Free distribution will give you a competitive advantage. 3. You have a simple value proposition and process. 4. The marginal cost to service additional customers is near or equal to zero.