Rear mattress you can get from someone on the list selling a used one (first choice) or has a local upholstry shop cut a piece of foam for you and you make your own (more work).
Rear hatch struts I have for $18 each (VW), and brake master cylinder for $80 (ATE).
Changing the brake MC is not that hard just messy.  
Remove the instrument cluster.  You should get a turkey baster or something similar to pull the brake fluid out of the reservoir before changing it.  Then put some rags under it, undo the two fittings, and pull the electrical plugs off.  Now unplug the clutch hose from the reservoir (if you have a clutch) and undo the two nuts that hold the brake mc to the brake booster.  The MC should slide out that then just swap over the reservoir and install the new one.  Hook everything back up, bleed your system and you are done.

Hope this helps,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242