i think its mainly that inspired is probably producing 1000+frames a year,just for example(dont know really),and in comparison jaf were producing 50+ a year,marino 200+ a year.
that makes people think why its so much more expensive,because mass production should keep the single items price low.
but!!! inspired has more marketing costs,more shipping costs,at least 3 middlemen before the customer gets his parts etc.
being a fan of good old "local"(preferred,but not available here)craftmanship its quite good to see that a custom frame can be way lower priced than a mass produced one,giving me the hope custom framebuilders wont come to an extinct...
edit:as for ross´s question:in peru living costs are way lower than over here or in the uk,marino can give his frames away for this price because what he earns is enough to live over there,and he isnt a greedy guy at all
in the uk its impossible to go lower as jaf do,i think
edit 2:another point on my first sentences is that alu is cheese and needs more prototyping to get it even to work in trials lol