I've also picked up a few kilt pins on eBay. Originally, I was just being budget conscious (must cost less than $5) but I've come to appreciate the pre-loved uniqueness.

Silver plated maple leaf, which now resides on my MacQuarrie modern 13oz:


Brass shamrock penannular, seen on my New World Irish arcylic:


Thistle safety pin inherited from father's days as piper, shown here on my buddy's vintage Grant tank. My buddy now has a plain safety pin and this pin is safely back on my Douglas modern 16oz: