Hi, I'm a longtime lurker(2+ years), thanks for having me on your site! I'm just curious about Rubberset 400 Brushes? It seems like anytime you see them listed on auction sites that they are ridiculously priced.... I've seen them restored and wow, they are amazing, but is that it. Are they more rare than other brushes or is it the type of aluminum they are made of, or does it simply come down to their looks? Any Rubberset aficionados know the answer?