You don’t say what kind of products you sell, so I have to generalize.
Shooting product shots in the garage is easy and relatively cheap, if sound isn’t an issue. And if sound isn’t an issue, it may be that most of the walls are irrelevant as well, unless they are there to help control light and to create a visible backdrop.
If you plan to do all the audio as voice-over, then you really don’t have a “sound problem” for the product demos. Not until you want to use an on-camera spokesperson. Have a conversation with the other stakeholders about that limitation, and how to work within it. You can record audio in a closet, heck, some people record it in their very quiet luxury car interiors, then add it in post – it’s all a matter of what resources you have on hand.
No, your biggest problem is when someone wants to use the space for a conventional person-talks-to-camera bit. In your case, unless this is to be done more than once a week, and an office or conference room isn’t available, I’d go find/rent a space for those specific jobs. You could even do those in a nearby hotel, if the room has the right characteristics. The concierge’ may give you the eye, until you explain you’re not there to stage an adult type of shoot. 🙂
With that as a basis, let’s talk construction. You need the back “wall”. At a minimum. That could be a hung cloth curtain, or a hard wall, what they call a “flat” in the theater. The flat can be a simple 4×8 panel of press-board paneling for ten bucks or so, backed with a few 2×4’s and c-clamps to hold it up straight. It can have a sturdier frame and wheels or skids to move it with, and corner framing so you can clamp multiple panels together and bend corners. There are books in the library and illustrations online for how high school and college theater groups can make simple sturdy, multi-purpose flats.
I prefer a medium gray cloth, because it’s easier to store and move, and you can light it to make it any color you need. Stay away from trying to green-screen anything in the garage: I sense you don’t have the budget or experience pool to carry that off yet. You *could* pay a sign company to make you a big logo sticker graphic for the wall, or you could use a video projector on the wall to add logos, etc. But I like cloth.
Cloth bought large enough will not show seams, whereas, building a flat with standard 4×8 panels WILL, unless you’re using drywall. If you choose a drywall “back wall”, you need a frame of wood or metal, anchored to the floor and ceiling, or braced from behind, which takes up a lot of room. I’d hire a drywall specialist to put up the wall and gather all the materials, and get it to the basic finished state, then you can paint it yourself. Or, buy the really wide cloth sold at Rose Brand in NYC, and just worry about hanging pipe at the ceiling and laying chain at the bottom of the curtain, to hang it. If I had to make the 24-foot by 10-foot drywall myself, I’m estimating 2-300 dollars for all the materials, not counting how to get them to the site. Go to Rose Brand yourself to pick out the cloth and estimate that cost.
Lighting should be a separate discussion, once the “set” is designed, and you give more details on the exact uses the set will be put to.