Frogtogs are the only thing that fit my 6'5" 400lb body and keep me dry in inclement weather. I won't travel with out them in my ditty bag.
Now if it is an emergency and you need something fast and cheap look at Home Depot or Lowes for some DuPont TY122S Disposable Elastic Wrist, Tyvek Coverall Suit, under $10 they usually come with booties and will keep you dry.