You've kept the budget sane for the sleeping bag, at the expense of a little weight and bulk, you may need to compress it to have some room in that pack. and shrink your ridgerest by cutting as some have mentioned.

"some cheap tent from wal-mart" sounds scary. most are. I would acutally use a cheap *backpack* from wal-mart before the cheap tent. If you want inexpensive yet reasonable quality options for a lightweight solo shelter consider:

Six Moon Designs Lunar Solo - $235
Tarptent Sublite Sil, or Contrail - $199
Hennesey Hammock UL $189

If you want to just sleep under a tarp look at:
Campmor ultralite 8x10 tarp (http://www.campmor.com/outdoor/gear/Product___20069) $64
Which you could either pitch on trekking polse, and use a mosquito net under, and/or hang a homemade hammock under it with no problem at all.

Oh, and look at my list (linked below) and you can see what I take for clothing