First, explain to them you're from Canada and you prefer to have it done directly with you because the audiologists/dealers here seem to be totally inexperienced. They'll say OK and you'll pay MSRP $950. The Westone dealers here quoted me $1100+.
Second, try not going to any "recommended" audiologists on anyone's pages; they're all full of crap, including Sonus. Just google maps audiologist near you and and call each one of them asking whether they have experience in musician's plugs, and that you need impressions of your ears to take home. If they seem to have trouble understand what you're saying, hang up. My audiologist is a small place 5 mins from my house, and when I inquired about the above, they answered right away, giving me more details and etc. You'll know when you find a good one. Also, I only paid $15 per side for impressions.
Also, with the bite block, you're not supposed to bite it with your front teeth. You're supposed to use two, and bite down with your molars at the back of your mouth, smaller side facing front, rounded side bitten on. Your mouth will open really.. really wide, but it'll give you a perfect fit unless you're really uncomfortable with a tight one, in which case you might as well bite down with your front teeth and not swallow once, nor mouth your mouth a mm; only then will you have even a small chance of getting a nice fit on the first try.