We usually allocate a team per project who delivers results. We advise our customers what the best combination of price/value would be in a particular situation.
We usually set price based on team composition. Price depends on which (full-time, part time) and how many developers go into the team, whether we have a quality assurance engineer, a project manager and UI/UX designers on board. We use the estimated hourly rate of allocated team members which is defined by their skill level.
As for minimum price for the project we usually launch ones starting from 10-15k.