I just bought a Canon M300 off Ebay recently. A little older model from several years ago, but it's new and the price was good. Think the online store was getting rid of them. You can input via Romaji which is what I do. Definitely makes things quicker and easier. I also think with the Canon Japanese/English dictionaries you can select for English or Japanese menus. I know the M300 allows that as well as an older IDX-9500 I have.
I think some of the recent models allow you to enter kanji by drawing with a stylus on the screen. This would be a useful feature.