You could search eBay for the seller ronaldo101. I get 3.6-V half-AA lithium batteries for less than USD4 each by buying four at a time.
The best that I have done with Rayovac 840 4.5-V alkaline was USD20 for four from yukonmkt. Such is the scarcity of 523 equivalents that they are likely to run over USD25-30, but there is the Chinese Exell A21/A133, which also carries the other makers' numbers: 523, PX21, EN133A and PC133A.
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The best that I have done with Rayovac 840 4.5-V alkaline was USD20 for four from yukonmkt. Such is the scarcity of 523 equivalents that they are likely to run over USD25-30, but there is the Chinese Exell A21/A133, which also carries the other makers' numbers: 523, PX21, EN133A and PC133A.
de