This is just what works for me! I buy 1 liter of 100mg nic from MFS at there sale price of $45. They will sell it at 100% of either VG or PG or 50-50, 25-75, and 75-25, mixtures of VG-PG. I have found this nic base wholly acceptable for tobacco, coffee, and any other strong flavored recipes and the price is right!
For HIC's delacate deseart flavors, I also get Vaperstek Nic which is really clean but much higher cost!
Also I highly reccomend the mixing and recording calculator at e-liquid-recipes.com