I have a Nesco that I got used on Amazon for ~$35, works fine. I use it to dry ingredients separately (black beans, carrots, peppers, tomatoes, peas, beans, sweet potatoes, etc), which I store in vacuum sealed canning jars. When it's time for a trip, I simply crack open the jars and combine the desired ingredients with some sort of packaged meal (mac & cheese, Lipton/Korr noodles, curry packets, etc) in a Ziplock style freezer bag. The dried veggies add flavor, texture, and nutrition to otherwise boring and/or nutritionally lacking meals.
I find that dehydrating the materials separately gives me the versatility to control/experiment with portions and recipes and it greatly increases the shelf life, as there are essentially no fats. For example, I often add beans, tomatoes, and peppers, and chili seasoning to make a delicious chili mac & cheese. Also, I can add olive oil at the time of cooking to give the meal richness and flavor without risk of the meal going bad in the weeks/months between when I dehydrate and am on the trail.
Also, I avoid dehydrating ground beef, as it's a hassle and, after removing almost all the fat, has little flavor. Instead, I just add TVP (textured vegetable protein), which can be purchased in bulk at many Co-Ops or hippie grocery stores. TVP has a texture similar to ground beef and is about equally flavorless, at a small fraction of the price and effort.