Around here, $250 would be a great price.  I don't know about your area.
You should definitely replace the tensioner.  Water pump is more a matter
of personal preference.

My off-the-top-of-my-head step-by-step instructions:

1.  Remove the engine mount by the r/f fender.  You'll need to support the
engine.

2.  Take the belt loose.

3.  Unbolt the power steering pump and leave the lines attached.

4.  Remove the belt tensioner and belt.

5.  Remove the idler pulley.

6.  Remove the upper timing cover.

7.  Remove the r/f wheel.

8.  Remove the r/f splash shield.

9.  Remove the crank pulley.

10.  Remove the lower timing cover.

11.  Remove the mount bracket from the engine.

12.  Set your engine to tdc.

13.  Remove the timing belt tensioner.

14.  Remove the timing belt.

14.5  Replace water pump if desired.

15.  Install the new timing belt.  Different people prefer different
sprockets to start with.  Just make sure when installed that the sprockets
are still in time and all the slack is on the tensioner side.

16.  Install the new tensioner and pull the pin out.

17.  Reassemble in opposite order of disassembly.

17.5.  Don't forget to add coolant if you replaced your water pump.