When I listen to records I sit in the sweet spot and never walk in the room for fear that vibrations from my pine floors will make the tone arm bob up and down. Buying a good shelf at this point in time is out of the question. I'm considering making a wall mounted shelf. Will this project be worth while?
Not for a Linn. If that's the only option, then you have to do what you can manage. But Linn typically does better on a short, light, rigid stand with a loosely mounted shelf. If your floors are wobbly, then you would do well to spend some time and money on the floors.
Mounting the table on a shelf sitting on a bed of sand can solve the floor problem in most cases - but you'll need a fair amount of sand.