You'll find it easier to locate the information you want when you realise that in English it's 'Digital Recorder' - I assume you must be French-speaking but 'Enregistreur Numerique' doesn't translate directly!For that sort of price you'll have trouble - best is probably an Olympus but I'm not familiar with particular models. If you can get a Zoom H2 (probably not very much more than your budget) you'll find it's quite a high quality machine, though annoying to use thanks to unclear display and controls.
Whether you buy new or used, be sure you can still get supplies for it. One of my friends is now having trouble finding those little rewritable CD's for his machine..