Most Montessori infant and toddler environments have low shelves. They are a staple, essential for storing and displaying toys and materials in an ordered way that is accessible to the very young child.  I'm frequently asked for the measurements of our Montessori infant/toddler shelves. Rather than provide them here I've found a few DIY tutorials that may be more helpful! 

1. DIY Montessori Furniture at Playwood. I feel like I could DIY these! How sustainable, you can shift the pieces around and make something new when needed or as the child grows! Also see their Kids' Wardrobe. 
2. DIY Montessori-Inspired Shelf for Toys at If Only April. 
3. DIY Low Montessori Shelf at Woodlark. 
4. Montessori-inspired DIY Toy Shelf for Abe at Boxy Colonial. 

Also see the DIY Instructions for The Low Shelf at Voila Montessori. There are lots of ready made shelves on the market, you can see our round up here. But for the most budget conscious I suggest looking around and using what you have. In living areas the bottom shelves of existing book shelves can be used, wooden boxes or crates can secured together and used, and of course Ikea have lots of budget friendly options. Some budget stores also have wooden shoe racks that have low shelves and can be used or improved (you could also trim the wooden legs so the shelves are lower), also at a really good price.