there is no money in music. especially metal. none. this shit eats money, it's a bottomless black whole that sucks in all the money around it. i've known "successful" metal musicians that are broke. when you factor in all the time spent practicing, buying equipment, gas, etc, almost nobody comes out in the black. anybody who thinks they're generating money is just having the bill passed on and paid by somebody else. on the whole, this thing generates no money.
Sammaellofi, punk rock and death metal happened without the involvement of record companies, the next whatever that comes along will do the same.
these days, i think the best way for a band to promote themselves is to self-press limited, short-run stuff, whether on tapes or cd-r, make some handmade packaging, and send copies out to some of the more popular downloading blogs to attract attention. they're going to download your music anyway. and if 10,000 downloads can garner enough interest to sell you 300 cd-r's or 7", you get to keep all the money, you still own the rights to your band and your music, and your little bit of cash spent has gone much farther towards the goal of getting the name out.
DIY is all that's left, and all that works for bands. i've known plenty of bands that trusted their music to labels, or trusted their booking to agents, and got raped BAD. one in particular i remember was signed to a "big" american metal label, had to give half of their merch sales back to the label, plus if the pressing failed to cover the cost of recording and the (well known) producer's HEFTY fee, THE BAND was held liable. we were playing the same shows as them to the same people, but this whole organization that was supposed to be helping them was really just making them broke musicians. this shit is standard operating procedure for the conventional music system, and it's diametrically opposed to promoting creativity or proliferating any sort of true art. naturally, the smartest learn to stay clear.