Honestly, I cannot recommend the Nesco American Harvest series dehydrators highly enough. They're reasonably priced, well built, offer lots of useful upgrades and have their heating units mounted on the top. If you need to seek out a replacement, you really can't go wrong with a Nesco. Mine was about 70 bucks on Amazon, and that included two additional trays and some spill sheets.

Avoid any dehydrators with the base-mounted heating units like the plague. They're a major pain to clean up, and run the risk of getting fried if something liquidous gets dripped into them. Also avoid square units, because they just don't distribute the heat as evenly as round units.

Finally, a $7.00 roll of fiberglass window screen from a local hardware store will provide a lifetime's worth of cheap dehydrator screening for fine things, like ground meat, quinoa, rice and other food bits. The screen is about 1/5 the price of a pack of "official" plastic screens.

Hope this helps!