Any optics almost can be used as an eyepiece. The question here is the color correction for a camera EP as they are looking at a LCD with a fairly large pixel size of just one color and thus they really don't need color correction to see a good image to the eye.
Binocular EPs, on the other hand, are usually fairly well corrected for color but often have other problems like resolution and spherical correction.
There are suppliers of cheap EPs like Gary Hand that do some quite decent EPs for a very fine price. They're not PanOptic quaility but for the price, they're quite fine.