Much has been made of selling man portable anti-aircraft weapons to rebels in one civil war or another. The biggest fear seems to be that they could fall into the hands of radicals, and be used on air liners in the West.
Why not sell anti-aircraft guns in the 30mm-76.2mm range with modern rounds and fire control systems?
A 76.2mm round with a guided shell and fired out of a rapid fire weapon should be quite devastating even to fairly modern jets up to ~15,000 feet. 30-57mm weapons with modern fire control systems should fairly easily push aircraft above 5,000 feet in order to lower loss rates. In addition, the weapons are readily available from virtually any of the Warsaw Pact nations, so it's not like there's much of a worry about them finding their way into the black market. Finally, they are just too big to really smuggle anywhere in the West, unlike a MANPAD. Yet they are easily small and light enough that any rebel group with access to "technicals" would be able to tow them into position.