Walmart offers the Better Homes and Gardens Leighton Twin-Over-Twin Wood Bunk Bed in several colors (Black pictured) for $159 with free shipping. That's tied with our mention from two weeks ago and the lowest price we could find by $28, excluding the mention below. It converts into two separate twin beds, and features guard rails on the top bunk plus an integrated 4-step ladder. A close price: Hayneedle offers it in Light Cherry for $161.68
With these companies, it might be easier than you think to negotiate your monthly bill down.