This keyboard bench and stand kit is a good model in terms of quality and prices. Here's the specs:

Keyboard stand:  

• Fully adjustable  
• Folds flat for storage  
• 3 cm x 3 cm (1.2 in. x 1.2 in.) steel frame  
• Adjustable height:  58.5 cm to 87.3 cm (23 in. to 34.4 in.)  
• Maximum load: 49 kg (108 lb.)

Portable bench:  

• Soft, padded seat  
• Steel construction  
• Sturdy locking system  
• Foldable