Recommended battery pack for HP-19C?

[Joe Horn]

A tedious Google search revealed that 4-AA NiCad battery packs for the Sting Series calculators (HP-10 and HP-19C) are available online from multiple sources, but they all seem to be $50 or more, which seems excessive, and I don't know which sources are reliable. Yes, I know that I can rebuild the ones that I already have, but I'd like to also buy some more as spares.

If you have purchased a Sting battery pack online, please share your impressions of it, and your source, and the price you paid. Thanks in advance!