Any rescue worth their salt, wont let you adopt one pig, unless you already have one at home.
Pigs are social creatures, they need same species companionship. I'm going to give you a scenario:
Your on an island, alone no humans, their is a monkey there. Sure you can talk to the monkey, you can hang out with it, but it's not going to give you exactly what you want back. And, eventually you are going to go crazy and talk to a soccer ball named Wilson (Castaway reference)
I have two pigs, and will probably get a third, after I find some steadier employment.
The difference between 1 pig and 2? Hardly noticeable, why?
Sure your going to double the pellets and hay, but honestly some hay gets wasted anyways. And if your pigs get proper veggies, they don't even eat all their pellets anyways.
As for vegetables, I find I waste less vegetables with 2 pigs then if I was to have one. I'm a very lazy cook, almost all the vegetables I eat are frozen or in cans. I know they don't have as much vitamins, but I just don't take the time for cutting/cleaning/skinning vegetables. The fresh vegetables in the home are for the piggies, and realistically if I only had one, I'd be wasting vegetables.
So please adopt two pigs, it is much better to have a friend. Don't give your pig a monkey and a soccer ball as their only outlet.