Cute shoes with a steel shank?

I like wearing high heeled boots (3+ inches), but the shank always breaks on the boots that I buy. I'm female and not that heavy (140 lbs), so I don't know why this is happening.. maybe I'm just too hard on the shoes. Maybe the shoes I buy are too cheap, LOL (I shop at zappos.com). Anyway, does anyone know where I can buy cute high-heeled boots that have a strong, reinforced shank that won't break in half?