Most front-loading dehydrators that have trays with adjustable levels, have trays larger than 9" on each side, and that have an adjustable thermostat will work well for this project. Our suggestions are from Amazon because they ship free with Prime and are readily available. It is quite likely units with these parameters can be found locally.
Facebook Marketplace is always a good place to check for a used unit.
Many people have Excalibur dehydrators already. They will work fine for this project. They are more expensive than some other options, however, if you are looking to buy new.
We were initially planning on suggesting this model from Amazon, as it struck the right balance between features and cost. It has 12 racks, which comfortably fits 5 trays of soil for drying, racks that were 11.6" x 11.6" in size (wide enough to comfortably fit 8" wide trays), high power (1200W), and a digital thermostat, for $160. However, it only has intermittent availability. Here is another similar model.
Our backup suggestion is the following model, also from Amazon. It shares many of the same features, but has a slightly higher price point ($209).
A similar model from Walmart also ships free, but may take a couple weeks to arrive. It is a lower cost ($165). Looks like it may ship from overseas from a third-party vendor, so likely limited return options.
