I found a good deal on a Haida filter set-up, similar to the Cokin, but less expensive.
It's a drop-in filter, with holder and adapter ring, the M10 series.
I used to deal in Haida filters and know them to be well-made with a more neutral color cast than most other brands.
And after comparing the way the Haida and Cokin filter holders worked, I decided I liked the Haida method. Looks faster, more stupid-proof (very important for me).