"I love bow ties but have very few shirts to wear them with, so I’m hoping that you can recommend an inexpensive dress shirt for someone of my size & shape. Even smaller slim-fit men’s shirts run too big in the shoulders and neck, but women’s dress shirts are often missing a button at the top of the placket (because of course I want to show cleavage?). I’m also fairly tall, so I need something with longer sleeves and torso, and then there’s my b-cups to accommodate. Is tailoring the only answer?"
Depending on your aesthetic and budget, a few places come to mind: Brooks Brothers, Uniqlo, L.L. Bean and Lands' End. Uniqlo's men's Easy Care Slim Fit shirt may be a good bet for you, and right now, it's $24.90. I've had a lot of friends and clients report that they've had good luck shopping in the boys' and women's department at Brooks Brothers, and the women's departments at L.L. Bean and Lands' End (their silhouettes can often be tailored but not over-feminized or cleavage-inducing). Whatever you end up with, tailoring is always helpful for perfecting a shirt so that you're as comfortable as possible. If a shirt or its sleeves are too long, for example, and you have an extra $20, you won't regret spending it on good alterations.