Those costs will highly depend on the kind of music and your ambition. In my opinion many artists do not actually need professional mastering. If recording an album is a loss anyways, why not make your music free and see if you can find enthusiast hobbyists to do the fine tuning for free as well.
It's certainly easier to DIY these days for some things -- electronic music comes to mind, but there's no replacement for a properly treated studio with all the appropriate equipment on hand. You get what you pay for.
> many artists do not actually need professional mastering
Almost everything sold commercially has been mastered, the only stuff I have heard unmastered is on Soundcloud/Youtube for a reason. Having a skilled third party polish a track is essential.
> why not make your music free
Why is this acceptable for a musician but not for a film director, actor, programmer, or any other career professional? Should all films now be made DIY with volunteer actors and we'll just have hobbyist special effects and post added? What are these hobbyists supposed to do to pay rent and eat?
Music is an expensive business, and digital downloading hasn't changed that. That's why it's frustrating to hear people feel entitled to free music, even if there's not much we can do to change it.
