Sometimes it's best to just dive head first into things. So, for the first run of the "real" collar pin, I decided there was no better shirt to stab holes in than one of my made to measure numbers that actually cost me a considerable sum of money.
big fat shawl collar sweater. Got a nice 1930s vibe about it, no?
As a side note, I've discovered that paired with flannels, a big navy cardigan makes an excellent casual alternative to a blazer, and it has been officially decreed (by me) that a cardigan is best when it's long enough to wear it with at least three buttons open at the bottom.