The Bdellium brush kit includes 12 specialty FX brushes along with a "double pouch" (2 pouches which can be connector or used separately to carry brushes). The best value is in purchasing this kit (individual brushes are available, but add up to much more than this "set").
Included are a nice range of brushes from a splatter brush (toothbrush looking tool), Angled brushes to get into difficult areas, a varity of stippling brushes, a neat Muscle-brush, detail brushes for veins and capillaries and specialty adhesive brushes.
I found the quality to be very nice - they've got a good look to them, are well made (using harsh brush cleaners had no impact), and will make a nice kit. I'd first look into which brushes you need and weigh the cost of those individually vs. the kit.
These are brushes you'll want to care for, so you'll want to avoid materials such as Latex which will ruin a brush. I've used alcohol-based paints, blood effects, airbrush paints and more with these and all have gone back to normal after a quick cleaning. For cleaner, I've had great luck with the Cinema Secrets brush cleaner which works great on removing special FX products.