I'm rather surprised--and somewhat baffled--that there is no demo, because Orbx's own returns and refunds policy states:
Change of mind
Please choose carefully as refunds are not provided for change of mind purchases or if you have made a wrong selection.
We recommend you carefully review the product information and any orders before proceeding to checkout.
Orbx Simulation Systems Pty Ltd also provides gigabytes worth of demos and freeware items to clearly demonstrate what our products do and how they will perform on your PC. Our software is tested across various systems during the beta phase and is released with confidence that it works as intended.