G'day I don't know where you live, but many places sell portable dog runs such as carrington kennels, colwestern etc, alternatively its quite chea to diy with star pickets and either dog wire tacked on, or those stratco fencing panels which just slip over the star pickets. Personally I have done 100 mill posts and dog wire for a dog yard. very cheap.
Also if your dog is a climber then you might want to thoink about an inverted to for a fence, diggers need a barrier etc.
I built my dog yard for about 400 but its huge with posts and 100m of wire.
If you find yourself going through hell; Don't stay. Just keep on going.