I can vouch for Accessories4Less. I really thought it was a troll/scam site, but a colleague of mine had purchased A/V equipment at some great deals over the years. I ended up getting a top-of-the-line Onkyo receiver for $250. Only caveat was that it was a refurbished unit (i.e. returned less than 14 days.) Although it did fail four years later, it was a known manufacturing problem, and Onkyo did good and replaced it for me at no cost.
I've since purchased a few other receivers from them (currently a Denon) and a Harmon-Kardon in the past. Do some digging too because your local electronics store may likely wheel and deal. Most current-market receivers can be controlled via smartphone, so keep an eye out for that. I don't have enough experience on outdoor equipment, or what your intended setup/physical constraints are like, so if weather is a factor, you may want to keep that in mind. If you want to drop some serious coin, consider a Sonos setup, or Yamaha's wireless setup for starters. If money is no object, well then...