Particularly one that is easy to use and not too difficult to assemble
Kyocera ceramic, for about $25. No need to spend more unless you're doing professional quantities.
I've been using this MIU Professional for about 2 years, since nearly making waffle fries out of my fingers with a handheld mandoline that didn't have a food pusher. It requires no assembly, is very easy to clean, and the stand makes it nice for large quantities.
I have the Bron Original Stainless Steel Mandolin Slicer. I got mine at a restaurant supply store which gave a pretty nice discount to culinary students, which I happened to be at the time. I think I payed $60 for mine. that was about 3-4 years ago, and it will still take your finger tip off if given the chance. I use it several times a week.
This is one of those kitchen tools that I would tell you that its worth saving to get a high quality one.
No matter what Mandolin you purchase...they require a blood sacrifice at some point.
I use the Japanese Benriener. I find the only difference between it and the stainless steel models is price.A thin cut vegetable is - a thin cut vegetable.(I used the money I saved for some nice wine...lots !)
Years ago I bought a very, very inexpensive one---came with 3 different attachments that just click right in for julienne, thin slicces, and thicked that julienne. It's been great, I still use it several times a week, and serves me very well. Sorry, I don't know the brand, but I do remember that it was cheap.
My mom always recommends any Japanese mandolin. Reasonably priced if not inexpensive, nice sharp blade, and lasts quite a while. She had hers for almost 25 years. I think she might still have it...