If your going into a place where you may not get water, say a desert, then there is little point in dehydration as you'll have to carry the water anyway.

The main market for 'dehydrated meals' are bushwalkers.. they do a fair amount of work and sweat - so they need lots of kg + salt... thus the meals have it for them. A bicycle tourer may need 6,000 calories per day! That is a lot, about 1kg perday dehydrated! If your sweating on your journey you too may need some extra salt and food... In Oz the cheapest place for them might be Dried Food for Hiking, Dried Fruits for Bushwalks, Multi Day Bushwalking Food

You can get some interesting stuff in the supermarket! The 'cup of soup' stuff + noodles do wonders for some. Weight saving can be had by not choosing something in a tin can.. Aldi Remano Couscous ( I like the 'Hot & Spicy') - just add hot water stir and wait a few minutes, you might want to add a sachet of fish/chicken. Sun Rice microwave meals 'only' need heating - they are precooked, no can. Coles - Indian section - Tasty Bite Bombay potatoes, Passage to India Dhal Manhani. And there are dehydrated fruits - they tend to have lots of sugar! Mango, banana, apple.

If you want you can DIY dehydrate .. then vacum pack. This works well as you can refrain from the added sugar and salt. And reduce the costs.

A word of caution .. all these things loose their nutritional value from the moment they are processed, at the expiry date there would be a fair loss! So buy and eat fairly close together, don't store. Not something you could use for an extended trip .. you might be able to plan a month, after that your buying what is available, or have a support person at home sending you out stuff.