[villagetinker]

I am not sure what "leaking seals" refers to, but if this is the seal between the panes of glass, you make check on just having the glass replaced, try Lake County Glass and mirror, Front Page - Lake Glass & Mirror.
If the leaking seals refers to the around the window sliding area and the frame, carefully check the weep holes and make sure these are not blocked, if they are, carefully clean these out and check for leaks again.
As for the cost, I do not recall the details, $150 per window for labor might be a bit high, but I have no idea what is involved on your house, stucco finish is different from vinyl siding finish, etc., if the entire frame needs to be replaced.