This is the Double Deck Bed Design 01, one of 10 sample picture of double decks for kids bedroom. I hope that this picture can be a reference when designing a bedroom for your boys. The upper deck is smaller than the lower, the stair was designed in simple. I think that it’s simple double deck bed can make a convenience into the bedroom.
Based on several sources, such as on Alibaba, the prices of single double deck bed are varioous. For metal double deck, the price is about $40 – $45 / set. For 3 sets the price is about $269 – $637/set, for double deck multi-purpose folding sofa bed, the price is about $500 – $1200/unit
Furthermore, here are all 10 kids bedroom design with double deck bed design.