You can run "dual zone" meaning play music outside and watch a movie inside using the same receiver. And you can do it for much less than $1,000. Yamaha, Denon, H/K, Onkyo, Pioneer all have models that will do what you want. I can't recommend any specific model because dual zone wasn't a need for me. I do know the newer H/K's will let you set different crossover levels for each speaker - which I think would be handy if you are trying to blend an un-matched 5.1 setup.
Point is you should have plenty to choose from - both used and new. I prefer slightly used or at least the closouts at your local A/V store.