OSH park is great if you're based in the US/Canada. Iteadstudio, Seeeedstudio also deliver great results, though usually with a longer lead time than OSH. I have seen several references to EU-based PCB foundries (Hungary?) that also offered very competitive prices for EU-based hobbyists.
I simply like professional-made products because those guys can guarantee that the boards are good (i.e. in-line testing of traces/contacts), the traces are sealed under a nice coating, you can have nice screen-printed overlays, etc. Much easier to get a great-looking result that will last.
I don't have the time or the inclination to handle dangerous chemicals in my home, install the right ventilation system to handle the fumes, and so on. With multiple small kids, it's only a matter of time before they get in the shop and I want to limit the potential impact that such an unauthorized visit might have.