I totally get your frustration and believe me, we are at least as frustrated as you are 
Because our intention totally is to provide batteries and stuff! Batteries weir out over time, it will become necessary to replace them. But shipping regulations really make it close to impossible to do this at reasonable cost.
I honestly have no good solution for the problem.
The batteries in the L13 and L15 are as far as I remember compatible with some Topstar types which can sometimes be bought from second sources.
The L13 battery type is: TU131-TS63-74, 7.4V, 45Wh
The L15 battery type is: U753-TS44-111, 11.1V, 48.8Wh
Maybe this helps?
Cheers
nicole