What does it cost to open this Revit file?
Rent a Seat of Revit
Daily, monthly and yearly subscriptions are available. Monthly subscription costs about $370. That gets you the ability to develop with a local desktop instance of Revit. Additional engineering SDLC costs mount from there.
Sign Up for Autodesk Platform Services
APS requires a minimum signup fee of $300, and prepaying with tokens that are consumed by metered billing. Basically $6 per hour of runtime. Please review the feature set on APS (using APS Model Derivative) to see if it meets your needs. Additional engineering can be done to add custom code to APS Design Automation, but you will need to build and ship that code.
Ask Your Design Professional
You may have an architect or engineer that has a seat of Revit, what is their hourly fee? $150 per hour? $250 per hour? You can’t develop a product this way, but you can at least pay a fee and open a file.
Buy HOOPS Exchange (Techsoft 3D)
Monthly / yearly pricing at the enterprise level and revenue sharing arrangements may vary. HOOPS uses ODA, and provides a limited feature set for moving data from Revit, to PRC and a variety of formats from there. Not all Revit data is supported.
Buy Open Design Alliance Membership
To use ODA there is an initial cost and a yearly subscription. This does not include hosting expenses and engineering effort to run it in the cloud or package it for desktop distribution.