Have you tried Latisse? It's $100/bottle, but one bottle lasts 2-3 months for me. As long as you paint it on your lash line, you avoid the iris pigmentation side effect. I like to drop 2 drops into the brush holder, then dip the brush into the liquid and paint it on my lash line. It works wonders after 6-8 weeks of using it. At this point, i don't even use it everyday (just 3x/week for maintenance) so my last bottle has lasted me 4 months