Don't get too hung up on the watts. Max wattage in a speaker spec isn't all that useful, sensitivity is a much more useful spec to approximate your amp needs for a particular speaker/spl desired. That's a relatively old receiver tech wise, particularly for 4k needs. Bluetooth isn't as good as wifi/airplay....some avrs have those built in, not sure about the one you got....
Hard to recommend what you might be able to get for your budget....if you're in a good sized metro area your chances are better than living out in the boonies like me. Where are you? Maybe some of us can help look at craigslist etc to help out. I'd at least try and find used before shopping at BB. Or if you've spotted some speakers/subs within your budget you want comments on, post 'em up.
Good luck on the hunt!