Since I started DIY, I haven't bought juice in a few weeks. I know what I'm putting in there, if it tastes bad, then I adjust to make it better the next time. I've found that I can only premium flavors for a little while, before they aren't as enjoyable to vape as they were at first. That being said, adding DIY to the repertoire, vaping has pretty much become self sustainable. I have my own wire, tools, and juice. I'll go to the shop to ask opinions on a juice, or get a drip tip or another mod, as I still like to support a local shop rather than a chinese E-bay seller.
That being said, there are only 2 shops around here are really knowledgeable that I'll go to. The third shop however is run by a bunch of people that don't really know what they are talking about, their juice is not the greatest, and their display cases are mostly just for class 1 vaper's, their juice is in the back, not in plain sight. They won't even help someone build a coil. It wasn't hard at all to make the decision to not go there anymore. Now if it was the only shop in your area, then maybe talking to the owner how to make it better would be better than not doing anything at all. I'll just stay away from them unless they are my last resort.
As far as the juice goes, I wear gloves, use a fresh sterilized bottle, syringe and needle tip if needed. I make it in my room, not a commercial kitchen, and nothing is going in there that I don't already know about. Is it overkill? Maybe, but when I sell a bottle of a flavor to my buddies now and then, it definitely puts their mind at ease, so I imagine there is a sort of mental block when it comes to something being un-sterilized.