Mike asks: Where can I find odd/less common suit sizes (my natural fit is a 45r, which is quite difficult to find)?
Some companies size more specifically than others. Some use S-M-L-XL sizing (blech!), some just go with even number chest sizing (36-38-40), some add short and long sizes and some go whole hog with odd numbers in the mix as well. The very best even offer semi-tall sizing off the rack.
Your best bet for odd sizes are traditional American retailers like Brooks Brothers and Paul Stuart. They consistently carry these sizes up to 46 or so.
After that, consider European-sized coats. You’ll find that the sizing translations are rough, since “subtract ten” rule of thumb is inexact. A size 52 Euro, for example, is actually a size 41, though it’s likely to be labeled a 42. A 54 Euro is about a 42 ½. You can learn more about how the conversions work here.
And of course there’s always the classic backup option: alterations. Buy something very slightly too large, and have it altered. Remember that the portion of a jacket that’s above the armholes is really tough to alter, but the waist is pretty manageable.
One good bit of news: when you have an unusual size, eBay can really be your friend. Strange sizes mean less inventory, but also much less competition. The odds that someone else is searching for a 45R coat and likes the one you like are relatively slim, so you have a shot at some great bargains in an auction context.