[Righty27]

Whilst not ideal but especially if working in relatively unchallenging projects, you should be able to upgrade to the latest PT version with your current Mac and then determine if you need to upgrade further ... and without doubt, you’ll be able to access the Sweetwater website.

Reading about nuances regarding Pro Tools performance in this forum might lead you to believe you need powerful, up-to-date hardware, however using features such as disk cache and adding some extra RAM can make PT 2018 run better than PT10 on older hardware.

FWIW, I would first upgrade RAM/OS and the give the latest Pro Tools a spin with your own projects before spending lots of $ ... and you’d only be risking the software upgrade (that you would require anyway) and some low-cost RAM e.g. from OWC :)