I would like to add something to this:There are some, yes. But you are suggesting that $400 will get you sound that is better than $100 will. Those that love the Yinman 600 ($129) think that they sound better than $400 sets as an example; though neither are DIY. So when I said yes, I meant that there are DIY buds on here that fall into the TOTL tier ($80-400) where sonic properties are concerned, and if you are ranking them by price.
If you'd be buying a flathead for 400€ I think you are expecting a balanced sound. Sure it can have a certain specialty - vocals to die for or crazy good imaging or crazy good staging. Or great bass quality and texture. Or a specialist for orchestra or a specialist for acoustic music. I think you'd even expects it to succeed on all those fronts!
If you are looking for a basshead signature, I believe no one is really willing to pay that much. Let alone a fun V-shape.
So if you'd want to buy the sound of the Destiny in a storebought earbud or from a maker, even if this special signature could not be done any better the max. price for this can be max 200€, even when it comes with a fancy cable, quality looking metal shell and mmcx or better yet 2-pin.
If you'd read the description "great fun V-shape, massive bass with great extension, crisp vocals and even treble response", you'd instantly be: "whaaat 400€?!? That's way too much for that!
So I believe there is a certain hard price limit for bassy earbuds. Probably not so much for earbuds with a balanced or bright leaning profile.