I love that stuff, especially combined with a yoke. As far as where to buy, I mostly purchased from people I knew personally. I hear that https://www.heartwoodsfurniture.com/ is great. It is operated by two women, one of whom is an engineer and the other who is a dominatrix. They are widely received from prodoms. If they can't provide what you are looking for, perhaps they can give you advise. This place used to be great at locating unique and authentic bondage equipment, such as shackles. I'm not sure if what the level of their quality and involvement is now. But, their site is still up.