The only problem is that you seem a little unclear of your size. 15.5 to 16 can be a large range. If you're really a 16, 15.5 will be way too tight. If you're really a 15.5, you'll look silly in a 16. I'd go to a decent store to at least get measured and maybe buy one nice shirt. Then get the others at a TJ Maxx sort of store.
I like Nordstrom Brand shirts, as well as Michael Kors for a good shirt that can be found under $40. Stay away from Express and Kenneth Cole. They may look nice, but quality is an issue with both if you plan on wearing these for work. Your best bet is to check out Nordstrom Rack if they have them in your area. They have a great variety, and quality brands. Or, find a brand with a cut that you really like, then buy a bunch of their shirts when they go on sale. Also, Charles Tyrwhitt has a sale right now, with plenty of items at $39-49. Oops. u are in Canada.. not sure about the conversion rate currently, but check out Nordstrom Rack if u get the chance
i asked a question a while back on the Charles Tyrwhitt and got mixed responses. I re-read that same thread and it contained a suggestion for the TM Lewin shirts. im leaing towards picking up some tm lewin shirts
as for the 15.5-16 comment, it depends really on the shirt maker. some shirts like the hugo boss fit well at 16, while others like the harry rosen house brand fit better at 15.5