I take it seriously enough to buy equipment/software (XLR cable, interface, mic, mic stand, bought my daw, bought the shareware version of UTAU), but the same can be said of any hobby. I don't think there's any such thing as a hobby that doesn't cost money. Even to do UTAU for "free," without paying for an external mic, art, etc. you still need access to a computer (unless you dumpster dive or someone shares their machine/donates something that's old). I would say it's one of the more expensive hobbies, given the average age of users in the fandom (the only hobby that probably tops it is video games if you're a PC, console, or Nintendo handheld player).
You can never make a livelihood out of it. I would say that it's almost insurmountable to make a career in the arts at all unless you have a lot of [rich] connections who can afford to spend frivolously on life's pleasures such as music/art. At the very least, you would probably have to be among academia or working with Votro Labs/Yamaha themselves to make a living at this kind of thing.