Ok, let me make it crystal clear.
Whitigir was comparing the cost of Focal Utopia plus a cheap amp, vs SR-009 plus a TOTL electrostatic amp. Now that isn't totally fair as a TOTL headphone and TOTL amp should sound better than a TOTL headphone and a cheap amp, but we're playing a cost game here, so OK.
The SR-009 and SR-007 MkII are comparable TOTL Stax headphones, with the SR-007 being significantly less expensive. At a recent Albuquerque meet, about a half dozen people got to hear both through a BHSE and half preferred one, half preferred the other, so an SR-007 is a viable alternative. BTW. Utopia sounds tonally closer to an SR-009 in my brief audition at that same meet.
Whitigir has built a couple Gilmore amps, which cost probably around 3K each. The SRX Plus is a stat amp that is comparable in sound quality to a KGST (in direct comparison between my SRX Plus and a friend's maxed out KGST), and can be built for around 1k. So, SRX Plus at 1k, plus SR-007 at 1.5-2k is 2.5 to 3k total, which is less expensive than a Utopia alone.
This has NOTHING to do with DIY headphones, which is another topic altogether, although there are a couple of apparently very impressive DIY electrostatic headphones floating around out there, including a couple built by Currawong. AFAIK, nobody is going to attempt a DIY beryllium diaphragm.
Are we clear?