For small busse's, you have a few choices
In the older styles of knives that your going to have to search for and hope you find a seller:
SH era mean street
4" filet knife
3 finger
lil' ugly
police recruit
In the one off catagory:
EDC prototypes
bad apple
Pepper shaker
These are a little newer then the really old hard to get ones above:
assault shaker
4" pbf (killer bee)
tanker a (combat 4)
basic 3
And of the new line, wich you may be able to get just because a lot of people have them and are current with the busse market regarding these peices:
active duty
(leaner) meaner street
new game warden
skeleton key
pork belly skinner
The smallest of the group = assault shaker and skeleton key. for general purpose, i'd say the skeleton key is better since it has a longer cutting edge, and isnt .25" thick. its still really strong, its just not designed to be a prybar. I personally carried mine in a calf sheath when I had it, and it was reletively sheeple freindly. Well.... It would have been if I didnt have to pull it off my calf every time I used it.
If your willing to go a little bigger, my vote goes to the crinkle coat basic 3 (mod-infi, smaller choil then the smooth coat version), or one of the recurved tanker a (combat 4 in europe) variants. the active duty was a good blade when I was using it, but the choil bugged the heck out of me.
Regardless of what you choose, your gonna have to look for them on the after market. the skeleton key, assault shaker and possibly basic 3 are probably going to be the cheapest that you can find.
If you want reeeeally small, see if you can find someone to sell you a 3 finger
