It really depends on your location and how much you are willing to pay for shipping. A good place to look would be pricing comparing sites like Nextag: http://www.nextag.com/folding-cart-with-wheels/products-html
You can find wholesale utility carts with wheels online. Some sites include www.rubbermaidwholesale.com/rubbermaid-carts/, www.nextag.com/utility-cart-wheels/shop-html and www.amazon.com/b?ie=UTF8&node=490895011.
Go to your local Sam's Club if you are a member or you might try Home Depot or Lowe's. Many businesses offer utility carts and since yours is for home use you may be able to find one at a lower price than if needing for commercial uses.
You should find the cart you like. Then call the manufacturer about ordering them dirrect. There are several online wholesalers for rolling utility carts. I would use a search engine to find contact information for the nearest utility cart wholesaler in your area.
A utility cart can be found at a local hardware business or even a supermarket. The best way to find various offerings of utility carts would be to research it online through multiple companies.
The folding utility carts were first created by a company known as folding Inc. You can go to the website FoldingInc.com in order to find out more about these.
All utility carts are resistant to the type of damage you mention. ULINE sells stainless steel carts, but I would go with sturdy plastic carts for the best protection.
One can find parts for Funder Wheels go carts on online stores or DIY go cart forums. They usually include wheels and other parts for different go cart brands.
Depending on the purpose and size required you can find information on getting a utility cart for a variety of places. Smaller utility carts can be easily purchased from retailers such as Amazon or Ikea. However, if you need a larger utility cart you are able to rent them from places such as HSS Hire.
A rolling utility cart can anywhere from $21 to hundreds of dollars. Heavy duty carts cost more but you can always find used carts for sale.
You can find a wealth of information on vending carts at www.WEBstaurantStore.com.
You can find folding carts online at sites like eBay and Amazon. Nextag and Target also carry them and bizrate is another site that carries folding carts.
Caster wheels seem to be made of harder material. Caster wheels are normally what you would find on shopping carts at stores or even maybe some toy wagons.