How much is tattoo machine cost?

They cost hundreds of dollars.

You can go online and find plenty of tattoo machines that cost $25, but you'll get about two pieces out of one of them, and you won't like using them.

Also remember: having just a tattoo machine is useless. You also need needle tubes, needle bars (they have the needles at one end and the loop to connect the bar to the armature of the machine on the other), a power supply, sanitation supplies, inks, to know how to tattoo...