Definitely +1 on letting a true mastering engineer do the work.
With home recording technology coming as far as it has, the mid-sized pro studios are slowly falling into extinction. Even commercial production houses are setting up their own small recording suites because, in the long run, it is cheaper than paying for studio time. Larger studios will always exist, for the simple reason that if you want to record an orchestra, you need the physical square footage and a 120 input console to accomodate them. The same is true for mastering houses in the sense that signed artists are not going to master their records by basement mastering engineers! Band demos have existed since the beginnings of recorded music. If you record something at home, a semi-pro mastering engineer may be able to get you what you need, in the same way that tracks that were recorded at a home studio probably didn't go through boutique tube mics and preamps.
It all comes down to "you get what you pay for". If you have a buddy who is a mechanic and has some pretty good tools, you might trust him to give you an oil change or change your brake pads, but if you had a race car that needed dynometer testing, you'd have to go to a pro.
I know that the analogies here aren't always 100% on the mark, but you get the idea :glasses9: