Quality of parts is one thing, volume of sales is another massive factor...
The same component will cost you more to make and sell the less you make of them...and that cost is passed on to the customer. Setup and tooling is amortised across the volume you produce
A rough example...not accurate in any way, but just to give you an idea...
A kit costs £200K in tooling and setup, £50k in development, marketing, etc.
Durango sell 1000 kits say...that £250k setup is split across those 1000 kits...so before you've actually bought the materials, or made any kits they've already cost you £250 per car! You then make the parts, and package them, send them to your distributors...the price of that needs adding as well....
Associated sell 10,000 kits say...so straight away they have a big advantage...each of their kits only have say £25 of setup cost to recover...they've already got a £225 advantage on the likes of durango.
It's a very rough, and nowhere near that simple in reality...but gives you an idea!
