Kahr MK9 is a small (not tiny) stainless steel, single stack 9mm. About 23 oz IIRC, very pleasant shooter. Here is one for sale for $600.
http://www.thehighroad.org/showthrea...light=Kahr+MK9
HK P7 is likewise a slim, blued steel single stack. Similar weight and size, also very pleasant to shoot, and exceptionally accurate (frame mounted barrel, excellent trigger). Last one I bought was about $600, but last few I have seen for sale are more in the $700-750 range.
Neither is terribly common, and neither is cheap...but in that size/weight class, I can't think of anything better. Sometimes you get what you pay for.
The current market has a lot of pistols going crazy price wise. That said, single stack pistols are not deemed to be in imminent danger of "hi-capacity" bans, so they may not sell as quickly, and their prices may not have risen as quickly.
Good luck, and happy hunting.