webecedarian 0 Light Poster

Is there any possibility of getting batteries for a very old desktop computer in NYC?

I'm told I need:
P/N 30807 CK-SUM 3A00
SYS. 333 S/L REV A03
and
840 (4.5. volts)

The person who's telling me they're unobtainable doesn't speak much English, and I'm not sure he really knows. And when I called Dell, they didn't know what I was talking about, even though it's their own product! (As a matter of fact, I'd also be grateful for any suggestions of a competent affordable computer repair place in Manhattan.)

Suggestions are appreciated!