The cheapest route for shade cover, a few silver tarps, might not be advisable for added weight to tent and potential "sail" effects in wind.
I think not wanting to spend $500 on shade should have you consider the tent inside a tent idea expressed above. As said, allow ventilation for the big tent.
I would cost a LOT to do aluminet, but it packs easily and I've known people who put it right on the tent fabric and it CAN work that way and doesn't become a sail, although it can't be as efficient as if it were suspended. "Green/brown" camo laying on tent fabric does very little except make nice shadows inside the tent, and again, you might have the additional weight problem, although reduced sail problems.
You could get "snow camo" and the whiteness would help reflect some heat, (big discussions on eplaya about white vs. black shade for keeping cool) but it is expensive also. See http://www.camonetsusa.com
if you what sticker shock.
Of prime importance to sleeping past about 8:45-9:00 in the morning is SIDE shade, on at least two sides. That adds a lot more complexity in set up materials needed and time involved.
If you think of using any shade material suspended by its own structure, and not dependent on the tent structure, for that size tent you will need at least six (maybe eight) strong, support poles, guyed with two ropes each, with 12 or 16 deep candy-cane rebar or auger anchors, and you will have to really torque down on the rope or wire you use between all the poles. It will take a lot of time
to set up the support poles, and keeping them upright while attaching connecting ropes/wire is a job for more than two people. It is also done best with two ladders. It is a very time consuming process and if it's windy when attaching such huge pieces of shade material, it will just make you want to cry....
Best of luck. Perhaps the cooler will be enough.