250mg seems exceptionally high (in reference to the OP's response below). The esketamine nasal spray that was just approved contains only 28mg per dose (1-2x/week). I don't know if that's because you need more if you take it sublingually. Snorting/nasal is almost certainly the most efficient/most effective way to take it.
It's not just about the expense, ketamine can damage liver and kidneys, and reduce iron uptake. Efficiency, in this case, is more about harm reduction than expense
