should I suspend a floor-standing turntable?

Toxic,
Where are you located? I just happen to have a very good sounding for the money 4 shelf rack that is a definite step up in sound vs. my own super solid built wood rack with spikes on both. It also sounded considerably better than a custom wall mount shelf I had. I was very surprised at this fact. Would sell cheap because I now have a pretty darn expensive and awesome sounding rack which I'm currently having made into 2 shorter ones very soon. I'm in the Chicago area. I don't have the boxes it came in so local would be best. Plus all the rods are already filled.

Put a few very heavy concrete paving slabs stacked on a sturdy table.
Optionally a slab of maple.

Unfortunately I live in Southern California. Thank you for the offer though Dorkwad.

and @Brf I live with my parents (I'm a student) and I don't think they'd let me do the mounting, hah.

At this point, I'm considering just buying a block of maplewood or granite and somehow affixing it the floor. My desk is quite wobby as well, and there's not really a place to put a turntable. Does anyone have suggestions for places to acquire such wood blocks for cheap?

Although these are fairly expensive, they illustrate the kind of arrangement I would suggest. A maple block on top of rubber/cork footers. I think you might be able to find similar material for the footers less expensively at Home Depot, or via Amazon.com (search for "vibration damping pads"). Or you can buy the "Isoblock" footers from Mapleshade separately for $24, and obtain the maple block elsewhere.

Regards,
-- Al