Also, you can tone the vandykes with palladium or platinum, which replaces the silver metal, and have for all practical purposes a print that is just as permanent as a pt/pd print made in the traditional way for a fraction of the cost.
One of the disadvantages of vandyke, at least with the green AFC, is that you have no contrast control. Not a problem if you make digital negatives, but can be a big problem with in-camera negatives where the contrast tends to range widely.
You might also consider true kallitype, which uses ferric oxalate as the light sensitive iron, like palladium and platinum. This process offers extensive tonal control with the dichromate contrast control method, which is also used by some with regular pt./pd. printing. I have an article on this at www. unblinkingeye. com, and also at the alternative photography site. http://www.alternativephotography.co...kallitype.html
With all these processes costs vary widely depending on whether you print with a kit or buy the metal salts in large quantity.