Essentials -I agree with the above although I'm only just considering a type of portapotti now. I haven't wild camped so have had no need as yet....so fill the space with other 'essentials'.....
*Camping seat for outside
*Fold up step
*Levels
Spirit level
Windbreak (though not used much)...cheap on does
Quechua shelter as garden shed
Dog crate....vet bed is then my 'carpet'
Eagle Creek pack it bags...different colours for different clothing items eg knickers, sox, fleeces, dressy gear, etc...they make storage and finding clothes so easy
Ziplock bags! I use these everywhere, and label contents so that when they're empty I know what I need to refill them with: pasta, rice, muesli, dog food, foil, loo roll, etc etc
Start buying small containers of things - small is good! They can then be refilled using normal sized purchases eg coffee - the new wholebean instant coffee containers are great size.
There are thousands more ideas of 'essentials' and it will depend on the kind of camping you do
I forgot: tin opener, bottle opener, matches! And screw topped wine bottles!
Supermarkets are a good source of cheap stuff: cutlery, picnic plates, Tupperware,