This doesn't seem the best sub-forum but I can't find a forum in the jobs area - mod please move if so!

We're looking to advertise non-game work for projects that use almost 100% game dev technologies. It's always been a challenge - we've used Upwork, StackOverflow, etc, and advertising on all of them is expensive if you only want one part-time person. I guess Upwork is the biggest pool but is not specialist and the decent people are in the minority so a lot of sifting is needed.

Where do decent, solid game developers look for work that they won't be competing with $5/hr hackers? 

People use their social networks (the people kind, not necessarily the web sites).  Talk to friends, ask about friends-of-friends, that sort of thing.

If you're involving the social network web sites to work the social network people, that involves posting things like "Can anybody recommend a person to do this thing?"

Have you tried cold-calling actual devs?

It's hard to work with someone through online especially when we talk payment options and making it official. 

First option i've seen is you can contact big companies in your country or locally and if they offer the option to hire one of their groups to work on your ideas for royalties it might be an option.

Usually these companies try to buy your ideas and offer you royalties instead, i believe some can be reasoned with. Depends on the negotiation part.

Some companies let their dev teams to have side projects they are passionate about, you can also send posters representing your idea and the details, some might want to pick it up after work. At least you'll be getting real developers

Edit: oh i understood the question a little differently.  A lot of the answer applies too just little reversed