Yes I should take photos of mine but in the meantime, here's the link to Bill's page:
http://www.merchantbass.com/acoustic/cextension.htm
The cost was USD 1400 although I think it's usually like $50 more or something like that for the cost of the string. I didn't have a chance to get a string and Bill had a Spirocore lying around so he gave that to me.
It is a lot of money but I feel like I have a whole new instrument. I actually wanted to put one of Bill's extensions on my previous bass but did not think the bass was worthy of it. My current bass is a much more resonant instrument and the extension enhances it significantly. It's not just about having the lower notes but it's what you can do with resonance of the instrument. Especially for playing arco, being able to set the low string to a suitable note (e.g. D for pieces in G or D, or C for pieces in C or F, etc.) just makes the instrument sound so much better. However for jazz work too, it's wonderful for playing pedals, low notes on ballads, etc.
What I like about Bill's extension is the refined appearance - it's not as big and obvious as some other designs and the Maple body with the Ebony fingerboard is nice. One reason for that (which I think also helps keep the cost down - I think his price is low at least compared to the other NY guys), is that he uses manufactured capos. He makes the latch for the E but the other gates are made from cast bronze. The design makes it very easy to alter the stopping pressure as well as the tuning of each gate. Bill also did a wonderful French polish job on the extension body and matched the varnish to the bass.
