Manual or automatic? The early Honda hybrids with manuals were the ones that had trouble with the batteries. 2000/2001 insight especially. If you run it at low rpm / high throttle and it'll give heavy assist and drain the battery pack. The automatic naturally avoids this danger zone. The changed the charge/assist programming and largely fixed that in the '02 insight, so likely the 03 civic has the new programming as well.
In this specific case, I think I'd jump all over it. I don't think age will degrade the batteries nearly as much as use, so this one is a good bet. (I think...
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