@Mike_Thornbury Thank you for sharing all that info! I ended up purchasing a couple hundred of the hammerhead tnuts from WangFang since their lengths are at 11mm. Slightly longer than the one OB provides so they will bite a little bit. I ran into the spring loaded nuts you linked as well but they are so close to Misumi USA charges so I opted out on those.
For US residents Amazon carries the low profile bolts that @Mike_Thornbury mentioned http://amzn.com/B00DD4STSA
and in black. I think I have their entire m5 set by now.
Amazon carries a lot of metric bolts and nuts. Cheap too at 100 counts.