yes - if you want quality stuff you need to build them yourself, I made and gifted a lot of these in Pakistan to freinds and family.
My own personal set had 600 amp all copper welding clamps on their ends but high power quick connect on the other, This way no one would borrow my cables as my car was part of the assembly to complete the circuit 
It would start anything - standby diesel generator, no problem..
We were discussing above that such items are not good for sale in Pakistan as a very limited number of people actually understand the value of these.