check with your local furnace and air comditioning business for used belt drive squirrel cage blowers. sometimes they have 1/2 hp motors that are still good and work fine. a 1/3 or 1/4 hp motor do not have enough power and will stop with little pressure.

the variable speed motor at lowes would be the best choice unless you can find a 1/2 hp motor at a cheaper price or free.

if your appartment has a small balcony with a railing you can make a table that attaches to the railing easy enough that will hold the motor.