Wireless on that budget just isn't feasible IMO. Plus you still have to plug in the speakers somehow. Running the wire is your best bet either via the carpet, baseboards or attic.
Surrounds are best put more toward the side than the rear so maybe that opens up more options. The angle of preference on surrounds is from 90 to 120 degrees from the seating area.
Putting speakers in a cabinet gets you a lot of resonances so you will want to line the cabinet interior. I'm thinking peel-n-seal would work fine for that on a budget.
You don't need a center unless your speakers are at a wide enough angle to warrant one.
For fronts use a pair of Behringer 2030p's. Unless you don't want a sub. In which case I'd suggest the 2031p's.
http://www.zzounds.com/item--BEHB2030P
For a receiver get an Onkyo 606.
http://www.accessories4less.com/make-a-store/item/ONKTXSR606/Onkyo/Tx-sr606-90w-X-7ch-Hdmi-Theater-Receiver-Black/1.html
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