You could take a look at Amazon.com and Amazon.co.uk. They ship to South Africa too, you should take a look at those websites as they have quite a large variety in laptop bagpacks.
There are many good sources for finding affordable toddler backpacks. The best places to find affordable toddler backpacks would be at stores like Amazon.
You can find affordable second-hand backpacks for sale at thrift stores, online marketplaces like eBay or Facebook Marketplace, and consignment shops.
There are many stores where one can find an affordable price for a Latitude D810. Walmart sells these laptops by Dell in all of their stores. These laptops go for about $150.
Lenovo laptops are considered very affordable by US standard. Most laptops in this class ranges from between $500 to $1000 and some online stores even offer them for less.
There are may stores where someone could purchase small backpacks. Stores such as, Target, JCPenny, Sears, Walmart and Champs Sports all sell small backpacks.
Small backpacks are often called daypacks or mini backpacks. They can be found at stores that sell outdoor gear, department stores, and online retailers.
Camping and outdoor pursuits stores
All PAC sun (pacific sun) stores sell Roxy and zebra print backpacks. If they are out of stock at PAC sun try justice for zebra backpacks
Computer stores
B.Csurf and sport and dakine.com
JanSport backpacks can be purchased online at JanSport. Backpacks can also be purchased on Ebay, Amazon, Zappos, Sportchalet websites. Many Army Surplus stores also carry a limited supply, but most can order the bag you desire.
Most electronic stores carry laptop backpacks. Places such as Best Buy, and H.H. Gregg sell them. Also online markets such as Amazon carry laptop backpacks.