I haven't seen anything to indicate there will be anything cheaper than $7. But if you need a data store, and who doesn't with a service that uses Heroku, I think you'll have to pay for that as well. For example, the cheapest Postgres instance is $9/month.

They are switching to an enterprise-oriented model, which means they'll nickel-and-dime you for everything. If you can't afford a few hundreds on basic infra, you really should look elsewhere.