My basic rule is clarity beats magnification any day. Meaning, for a set amount of $$, you are better off spending on quality optics at 10X rather than going up to 15x magnification. The higher magnifications require better glass. My personal example is having a crappy 60x spotting scope that would not show bullet holes in paper at 100 yards that I could see through my quality 9x rifle scope. That and the above noted need for a solid tripod. Maybe you can find a sweet spot of 12X and good quality glass within your budget.