So far, I know it is not possible to install Experience Service / without thingworx. So, means without Thingworx instance as part of the Experience Service installation there is no possible to publish and later to start in Vuforia view an experience. But:
I am not quite sure what you mean with install Vuforia experience- if here is meant if it is possible to review an experience - the answer is yes . In the Studio local installation (persist of installation file, node server + chrome browser) you can develop and review in the browser preview mode( chrome browser) the Experience project. But this should be only to get approximately impression how you experience should appear on the end device and it is not augmentation possible.
- if you use the option allow download for offline viewing - you will be able one time loaded from an Experience Service to start an experience on the mobile device in Vuforia View app without connection to ES
- you can purchase an PTC cloud account where you can use a PTC server (for the Experience Sservice +Thingworx instance) . About the cost it depends of the different feature you want to use and need to be requested by the PTC sale teams - also online