If you have RROD then it's possible to take apart the 360 using a simple tool kit, take off the X-Clamps and re-apply the thermal paste. Towel trick it after (videos on youtube). Mine worked for 6 months after. A more permenant fix will cost you more and takes a bit more skill because you have to replace the X-Clamps with bolts (again, there are videos on youtube).
Neither of the fixes should cost too much though. If they don't work then pick up an old arcade or something.