I have heard the best things about LL Bean beds - they are supposed to be really good queality and have a great warranty like others have said.
I'm sticking with relatively cheap beds for now (cause of the pee), and my favorite so far has been a target indoor/outdoor one. It's really big and has stayed fluffy for months and it is really durable and was only $40.
When (if, lol) Penny gets huge I will probably make my own. Zoey's old bed was home-made with a really sturdy fabric. I bought a huge peice (4 yards), then folded it in half and double sewed the edges with sturdy yarn, and put a zipper on the last edge (alright, alright, I had someone else sew it saince I can't sew
). Then I put a folded old comfortor and a box of polyfill into it.