I use a 7" Marshall (was around $1000, $1300 with batteries/charger), a 5" Marshall ($500) and a Zacuto EVF ($740 + $350 for Z-Finder). Out of those the Zacuto EVF is the only one that has multiple options for frame lines (2:35:1 being one of them). It really is a useful unit, really makes you feel like you are "one with the camera."
I think the Marshall monitors have different options for markers, and I'm sure with some trial and error and math you could figure out a way to have guides for shooting 2:35:1, but the EVF is the only one that has a quick, clear-cut option for that (that I am aware of). Then again you could always just buy a monitor, shoot a static scene on a tripod, pull it into your editor and add the 2:35:1 crop marks and then tape over the cropped areas on your monitor. Sounds tedious but it could save you a lot of money.