Just to clarify...
I personally think that if people are doing home recording for fun or for their own enjoyment or even for their band (because their band doesn't have the bux for a "real" studio) that they should indeed master things themselves. The learning will be worth it. But if at all possible, you should try having a pro master a single track...and if you're blown away by what they do, only you can decide whether the money is worth it.
Now if you're trying to do a demo for a "real" record company or break into the major leagues or think you have a shot at the national market because you are really that good, don't be penny-wise and pound-foolish...after spending thousands of $$ on recording equipment and countless hours in the studio mixing, let a pro tweak the final mix and you'll never be wondering if you coulda just made it if only...