I would tend to agree with the others. Low light gathering ability is usually the function of two characteristics, a large objective size and quality lenses and coatings. If you forego the large objective (40-50mm) in favor of a more compact design then you need to rely on quality lenses and coatings to gather the light. That does mean paying more money....Leica, Swaro, Zeiss, etc... My suggestions initially would focus around the 32 mm models of the top 3 (4 if you count the upper end Nikon) but the very least you would spend would be about $900 (for the Nikon 32 mm).

If that is too pricey then consider some of the $500-$800 32 mm models on the market. Zeiss Conquest, Kahles, Pentax SP series, etc.... The next step below that would be something like Nikon Monarchs, Bushnell Legends, Pentax XP series, etc... All can be found in both the 32 mm and 42 mm configuration and in fairly small packages to boot.