I too ordered a bunch of replacement feet for Sxa250's from PE. I still can't find that box!!!! I swear I'll sell the speakers and within a week the box will turn up.... such is life.
For the Sx300 - I might consider putting one of my assorted audio logs into service (strapping, 2x3, 2x4, etc - painted black with gaff or friction tape for friction) or a roll of gaff in a pinch. If you're in a wedding band or are doing corporate work you might want to consider a large font ACOUSTIC AIMING DEVICE label. You can then bill extra for them :twisted: !!!