I have looked for 3 days and cannot find anywhere that is carrying this kit. Why are they so hard to to find? But are there any other alternatives to hold 4x6 filters that are available?

Adorama has the rebranded Lee holder under the Century Optics brand. The foundation kit includes the 77mmWA adaptor so it is pricey but it is in stock. http://www.adorama.com/CYDSLFH77.html

Also Hitech has a brand new for 2012 competitor for the Lee holder but no one has tried it or reviewed it. http://www.bhphotovideo.com/c/product/834804-REG/Hitech_HTMHS_Modular_Filter_Holder_100mm.html

The Century Optics looks promising but the Hitech not so much. People said their 82mm adapter ring doesn't fit the 16-35 lens. Century Optics is a little more expensive than the Lee but at least it is in stock.

That Century Optics filter holder kit is made to hold the Schneider 4mm thick glass filters, and will not properly hold a 2mm resin filter, so you will be out of luck for it working with most common filters. You could get the replacement guides for 2mm and change them out if you can find those in stock, but that is more trouble and cost.

The Lee holder system is great, but the company has continuing supply issues for most of their products. I am very glad I have what I need, and still recomend them, but it is really bad to need to wait for a long time to get something from their dealers. An alternative is to look on eBay, where you can find Lee products sometimes going for twice there normal price, or even more.

I lucked out I found someone on here that was selling an extra kit they had.

Good to hear. Vistek.ca has the foundation kit in stock but its expensive at $169.95 CDN

If you are still looking speedgraphic.co.uk are showing stock but I don't know if they ship to the US

Get a list of authorized dealers from Lee Filters USA, see who does NOT have a website and then call them. You will be surprised what you may find. I bet you will have a foundation holder and a big stopper within a week.

The Lee supply situation is inexcusable. For at least two years the company has had DRASTIC undersupply issues. It takes a lot of skill to fix a constrained supply line in a matter of months. It takes an untrained monkey to do so over a period of 2-3 years. Now you know what I think of Lee.