i work for a dealership in dallas. we charge $350ish for a cv boot, $390 for both on 1 axle. for that proce you could buy a NEW axle from autozone.
with high miles the water pump and t belt should be changed. suspension parts may include control arm bushings, strut mount bushings and bearings, swaybar bushings.... these get old with time and heat.
oil leaks can come from different places. best plan is to jack the car up and take the belly pan off and get a flashlight to see where the car is wet with oil. could be a pan, could be a drain plug, could be the rear main seal, could be a valve cover gasket. all have different prices.
hope this helps.
-jd