These headdresses are made by Dancer's Choice which is aptly named.
Porcupine roaches are hard to make. Sounds like the maker sources the porcupine hides and gathers the porcupine guard hair and quills himself. The hardest part of roach making is sorting the hair into the different lengths. Another hard part is the base. If it's a premade cotton base, obviously it's not hard. A traditional base though is made out of deer tail hair that's been tied to a cord and then trimmed short and then sewed to make the base.
The rest of the time consuming build is tying and then sewing. It's the shape — where it spreads and how it tapers — is what really makes a well made porcupine roach stand out (although flat or upright is a style choice with flatter/spread roaches for grass and traditional dancers while straight and fancy dancers may prefer more upright roaches).
I would guess these porcupine roaches would run into the $500-$1000 range depending on length but probably best to ask the maker. Usual lengths are 15" – 24" depending on a dancer's style (e.g. Fancy vs Grass dance). Really beautiful work on these porcupine roaches.