depending on the prices, quantity, and quality the diyer spent to get their supplies... $10 a month could equate to A LOT of liquid... my wife and I together, my wife a very heavy vaper, and me a vaper that my set up uses more liquid, but not a heavy vaper... our cost is about 10-20 a month combined...
it costs, including the bottle, less than $2 for a 10 ml bottle... less than $4 for a 30 ml bottle...
the upkeep is really simple, start to get low/run out order more...
Since I don't use nicotine any longer, and most of my juices are single flavor (which I buy in large bulk size),,,,,,,,and I buy my VG and PG in quantity,,,,,
I can make 50ml for about $2.23.