A 12ft 4x4 (enough for 4 desk legs) can be had from Home Depot for $12.75. It might be structural overkill, but it's pretty cheap.
A simple sawhorse made out of 2x4s will probably need 20-30 linear feet of wood, depending on the design, which will $7 - $10 per sawhorse, or $14-$20 total. Building the sawhorses also takes more time than installing 4x4 legs, so labor cost is higher.
Of course, the 4x4 legs will likely need some brackets for strength against horizontal forces (e.g. leaning against the desk), so the total price including labor probably comes out as a wash.
A simple sawhorse made out of 2x4s will probably need 20-30 linear feet of wood, depending on the design, which will $7 - $10 per sawhorse, or $14-$20 total. Building the sawhorses also takes more time than installing 4x4 legs, so labor cost is higher.
Of course, the 4x4 legs will likely need some brackets for strength against horizontal forces (e.g. leaning against the desk), so the total price including labor probably comes out as a wash.