I've used cinder blocks (with 2x4's,) They are cheaper, easier and faster than constructing a wood or metal stand, and. imo, obviously cheaper than buying either.
You don't need special tools, special skills or much of a design. They can fit any tank size. The materials are easily found, easily moved and can be constructed and de-constructed easily to fit through any door or up or down any stairs by one person. No crews needed.
They have drawbacks: 1) negative aesthetic appeal; 2) heavier than wood or metal; 3) more destructive to carpet or wood flooring if the floor is not protected; and 4) can move laterally more easily than a properly built stand unless the tank is at least partially full.
Cinder blocks can be covered (with veneers) and of course the floor can be covered, but I wouldn't use cinder blocks for a very large tank (e.g., 240+ gallon) unless the strength of the floor was not a concern (for example on a concrete slab or a jack supported wood floor.)
I've used smallish tanks (75 gallons) in apartments (5th floor) with cinder blocks. The stand weighed 336 lbs (12 x 28 lbs each), while the tank was ~ 750 pounds.
For comps, the metal stand for my 180 gallon was probably 120-140 pounds, while the wood stand for my 55 gallon was probably 75 pounds.