The TS-e 17L is an expensive lens...and you are worrying about the cost of the adaptor?
Why spend money on the DIY adaptor when it inhibits the range of the tilt and shift...come on, why buy a TS-e 17L in the first place? Why not save even more money and get a 16-35IIL instead?
No need for sarcasm. I built the DIY before there was a Wonderpana. I rarely use it. It works. Give it a rest, guys.
One other point worth noting is that the benefits of an ND grad can be derived in software. Before I had my adapter, I bracketed shots and used the ND grad feature in Adobe RAW to replicate the use of an ND grad.
I don't use ND grads either. I haven't used an ND grad for around 5 years and sold my entire Lee collection to fund a 16-35 II L. The reason I use wondapana, is for the CPL and ND filter options. If I want to blend two exposures, often I want the sky or sea to be at a specific shutter speed and aperture setting. Often this can only be achieved with a set of ND filters, a tripod and a bit of careful metering.