IMO, this is as good as it gets in your price range: Minox MD-50. Available in both an angled eyepiece and a straight eyepiece version.
Minox is a German company that has been in industrial optics and cameras for almost a century. The MD-50 is a compact 16×30. While 30X is not considered to be “high magnification” as far as spotting scopes go, what makes the Minox a rare find is that even at 30X the resolution is very good. There are scopes out there in the same price range that have higher top-end magnification, but this is where the lower quality optics really show because the resolution just falls apart at the upper end of the mag range. Not so with the Minox.
I would think 20-30x would be enough for your needs at the stated distance. Also, IMO, top quality trumps poor optics with higher magnification. You can get a lot of 50-70x scopes, but if you find one that’s really useable at the top end in your price range, please let me know.
Currently there are open box models on sale at New York Camera Land at an unbelieveable price of $219. Yes, that price is correct. I’ve bought open box stuff from NYCL before and while it has certainly been handled, the full warranty is in place:
http://www.cameralandny.com/optics/minox.pl?page=62225_62226
Grouse