Walmart offers the Your Zone Premium Twin-Over-Full Bunk Bed
in Black or Silver, model no. 5563196WE, for $179.98
with free shipping
. That's the lowest total price we could find by $40. It features safety rails, a metal slat support system, and purports to hold up to 200 lbs. on the top bunk. It measures 78" x 57" x 63".