Any lash growing serums work for cheap?

Of course we all want darker longer lashes but dont have the money for the prescription Lattise so anyone know or tried the cheaper brands? ive been using Mega Lash's by Wet & Wild which I knew wouldnt yeild fantastic dramatic results but its yet to be worth the $4 so im willing to spend a lil more if i know it makes some sort of difference. I know the cheaper the formula the longer it takes to work but im willing to give em a whirl.