Whooha: I just converted OP's space to feet: 28' x 19' and over 15 ft ceiling height??
Total is about 8000 cuft !!!! That's HUGE space
Edit: Wrong math - it's 37.5ft x 25 x 20 ft - almost 20k ft^3
This setup would sound like speaker on mobile phone.
You can keep the AVR, but all the speakers needs to be upgraded significantly to even hope to perform somewhat good in that HUGE space.
If the measurements are right, I highly recommend this setup:
http://www.hsuresearch.com/products/hybrid3hppkg.html
specifically Hybrid 3 HP - 5.1 package.
After shipping and AVR cost+shipping - it's almost double your budget, but honestly you'd be overloading the poor Wavecrest to point of breaking and Dayton 1200 will do nothing but fart in that space.