I make my own Oil of Alkanet and it is not at all difficult. Purchase some Alkanet root and some Raw Linseed oil. You can use Boiled Linseed Oil but I have found that the raw works best. The difference between the two is that the "boiled" has driers in the mix. Simply decant a little of the linseed oil into a small jar add a little of the root and wait a week or so. You will know when it's ready or if there is enough root in the mix as you should not be able to see through the mixture easily. Some recipes suggest a small amount of "oil of the pine" (turpentine) but I have never found this to be necessary. A tip here is to make the colour a little darker than what you would like it to be and then more importantly wait two to three weeks after the last coat of oil before you begin the surface finish, the wood will become slightly lighter in colour. It does impart a lovely warm dark red/brown colour to good walnut. The root can be purchase from a number of places, I got mine from botanics dot com (I think!). Do not buy it from a place in B.C. called "Well Naturally" unless you like being scammed.
If you require any other info on stock finishing feel free to contact me.
Jim