I got mine at JensonUSA, but they don't have purple. I'm pretty sure you can buy items straight from Hope by calling them. I know you can order brake replacement parts like rotors and stuff so why not seat clamps? 
USA Sales
Hope Technology Inc.
40234 Dutton Street
Cherry Valley, CA 92223
Phone: (+1) 909-769-1654
Toll Free: (+1) 800-303-6863
Facsimile: (+1) 909-845-4467
E-mail: [email protected]
- Jeremy -
USA Sales
Hope Technology Inc.
40234 Dutton Street
Cherry Valley, CA 92223
Phone: (+1) 909-769-1654
Toll Free: (+1) 800-303-6863
Facsimile: (+1) 909-845-4467
E-mail: [email protected]
- Jeremy -