Hi there
If you know someone that does their own loading of ammunition they may have the ability to make the shot form raw led. Don`t know how widespread that is done anymore as there are hazzards to the fumes and such but there may be a few out there still. Other than that I agree it may be just as costly to have that done as it is to get more and then you have to put the shot into packages of some type. maybe the locak dive shop can give you a trade in deal for every 5lb they will give you one pound of soft led..
Take care and Best Fishes!! `•.¸¸.•´¯`•.¸>