Prices aren't set by one thing and one thing only, though.
Available cash flow definitely plays into the equation, and we can see this at work in a multitude of areas, from the skyrocketing cost of a university education, to the fact that ski resorts charge two or three times the going rate for a cup of hot chocolate (because if you have the money to go skiing, you have the money to pay extra for a hot beverage).
Costs also play a factor, of course. Dropping everybody's wages to zero doesn't mitigate the fact that raw materials, fuel, and even time are all finite resources.
Personally, while once a fan, I'm highly skeptical of UBI.
I would rather see something more like a universal assistance program: safe, government-run housing, dormitory style, with a cafeteria, available to all.
And I do mean "all". If Warren Buffet wants to bunk with Hobo Joe, that's his business. Buffet pays taxes that support the system, and shouldn't be barred from making use of it.
The people that live there are responsible for working to maintain the space: cleaning, cooking, etc. Put them near libraries and community centers, with ready access to whatever public transportation is available.
Unfortunately, given the current political climate, I doubt that this would go over well with either party.