The density of nicotine is 1.01 g/cm3 so for all intents and purposes, it weighs one kilogram per liter. But that pricing is presumably for pure, undiluted stuff, not the 10% (100 mg/ml) most of us buy. So figure $450 / liter of 10%. That's still 5-10 times as expensive as nicotine extracted from tobacco.$4,500.00 per kilo (approx 1 liter if I understand it properly)
So unless it has some big advantage when it comes to regulations, most people (and e-liquid makers) simply aren't going to buy it.