Are these guys serious?
https://bleasurf.com/collections/frontpage/products/beach-cart-for-blea-surfboard
198 USD?
You get these surf carts for less than 50 bugs on Amazon 
I can’t see anything which us custom on this cart …
Well, if you spend 10,000 EUR or more the additional 150 EUR probably don’t move the needle.
I don’t know if the cart is really custom, but even if not they have probably tried different models and have chosen the one which fits best.
I am using a similar beach buggy, but find them not very comfortable. It is time consuming to put on the straps and the boards are too heavy for a surf buggy.
I recently went for a slip cart for small boats. It does a much better job as you just put the board on it and don’t need to necessarily fix it with straps 
