STS radio battery - USA

Where can I buy, in America, a replacement battery
for an 'STS' brand hand-held radio?

I think 'Batteries Plus' can get one for about $70.

I've e-mailed 'Tropic Aero', asking if they have the
batteries. I think I bought my last couple from them
several years ago, but I don't know if they still carry
them.

Are there any other options?

Thanks,

Ray Lovinggood
Carrboro, North Carolina, USA