PC motherboards are manufactured in the thousands (at minimum) by large companies who benefit from economies of scale. Small boards are more 'boutique', often

PC motherboards are manufactured in the thousands (at minimum) by large companies who benefit from economies of scale. Small boards are more 'boutique', often being produced in the tens or hundreds (though there are exceptions), and components are also way harder to come by. For some of the little chips I've seen people use on these boards, lead times can be months (or even years now), and the pricing is astronomical (e.g. a chip that was $0.80 a couple years ago is a few dollars or more today—if it's available). And some manufacturers won't even pick up the phone unless you're ordering in the thousands.