Not all affordable lash crimpers are created equal, and some of them receive significantly better reviews than others. In terms of heated curlers that won't cost you an arm and a leg, the Ardell Heated Eyelash Curler is by far the consensus favorite. It's larger and a little clunkier than some of the more expensive models, but the results are the same and the heat is even, which isn't universally true of drugstore electric curlers.
Traditional mechanical models vary mostly in terms of shape and gripping ability, so you might need to look at a few. Not all curlers work for every eye shape, too, so think about how curved your lids are and then choose a model that's similarly rounded. If you're just not sure about your eye silhouette, E.L.F. Professional Mechanical Eyelash Curler is angled to accommodate a wide range of lid shapes, and the Tweezerman Professional Classic Lash Curler is also known for its versatility.