Sounds like the Vive is out of the question then, as the base stations (trackers) needs to have a certain amount of space between them, not to mention the need to be completely stabilized, preferably mounted to walls. That said, and don't make any purchases based on what I'm saying because I haven't had much hands-on with the Rift, but I do believe the tracker it uses can be placed on the desk in front of you and still work just fine. If that is the case, then assuming you have enough room for it (it's not huge) then this is probably what you're looking for.
You can get cheaper VR with things like the GearVR and emulate SteamVR through your phone, but it's just not going to be a very nice experience, plus the Rift and Vive has much more advanced tracking. While you might not have room enough for a roomscale experience, and while it may sound like a small addition, your head actually moving with your head in-game in all dimensions is incredibly important for immersion in VR. Not to mention, the emulation method isn't smooth at all, in terms of frames per second and tracking in general. In other words, it's not playable. The lack of proper head tracking is the difference between being 'in' the game and watching a 360 video on Youtube.
The Rift comes with an Xbox controller I believe, so if you think you can fit the tracker next to your monitor or something then it's probably your best bet. It doesn't absolutely require motion controllers, nor does the Vive but that's probably out of the question regardless.
You'll be a little limited in terms of games though, especially moving forward. Motion controls in VR is just as important for immersion as everything else, I'd say. But Elite: Dangerous is still my favorite VR game and it has a very basic implementation of it. But it is exactly what you're describing: a game that lets you be 'in' it without requiring you to change anything else about the way you play it. There's also ways to get non-VR games to work within a VR-environment, though this generally requires the use of a driver like vorpx, which isn't free, so I haven't played around with this much. From my understanding you can expect everything from games simply running on a 3D monitor floating in front of you in a void-like environment, to almost fully VR supported experiences. For example, apparently you can run the regular Fallout 4 in VR without all the motion controls and stuff of the VR edition of the same game. Then again, I have not tried this, so it's worth taking a look into the various drivers' support for the games you see yourself wanting to be playing if this is a big deal.
Edit: Forgot to mention, if you have the patience, I know several companies are working on inside and out-tracking or whatever it is they call it, where the headset itself keeps track of where it is, rather than relying on separate trackers. No idea when these might hit the market but I don't think they're too far away
Edited by Migokalle, 25 January 2018 - 09:58 PM.