Probably a stupid question, but I now some of the versions are supscripton based, but are there any one time purchase programs of Vegas?
Yes, and to my knowledge for both Vegas Pro and Vegas Movie Studio. Check here https://www.vegascreativesoftware.com/us/vegas-pro/product-comparison/?_ga=2.192507754.1907914609.1593663015-2017054007.1575168940
The subscription plans are currently VEGAS Pro 365 and VEGAS POST 365. The other purchase options are perpetual versions (i.e. once you go through the one-time purchase, you own the copy forever) including all VEGAS Movie Studios. Consider the Platinum version if you decide on a Movie Studio. Trial first.