Hi, you can find some info on the "Roomates" section of this forum. I'm actually offering one room, but I gather it's a bit above what you want to pay ($370). I'd suggest you to check it out, just in case.
There's also a Facebook group, Flats and Flatmates in Lima, where you might find some more info.
Other websites would be urbania.pe and adondevivir.com
Hope this helps!