If you get 100k (or whatever) you can always mix some looser stuff to get something less than that.
This will tell you what proportions to mix to get the viscocity you want. Just remember that the highest viscocity you can get will be no higher than the thickest one you have, and the lowest viscocity you can get will be no lower than the thinnest one you have. I guess it depends on what you have already...