Hmmm. $15 for 30mls isn't the pricey juice, even...
AT that price range, I'd suggest MrELiquid - I think they're better than Mt Baker Vapor...
What you want to do is chase specials - look for discount codes!
One place that always has a REALLY low price on certain flavors, but is also recommended as being good is Yaeliq. You've got to get a lot of liquid, so the shipping makes sense, but you could get 100 ml bottles for $10 ($18 for non-sale flavors) - but the shipping on one bottle's gonna be $10 (stuff comes from Israel!). SO.....$20 for 100 mls. But if you saved up and ordered like 5 bottles, that'd be a deal. And people do say it's good...