The fast 100 achromats are unsatisfying. It will annoy you with the chromatic aberration around the moon, Saturn, Jupiter etc., as well as high contrast views over land.
If budget is low then the Vixen 80/900 is excellent at f11.4 and I know from experience there is no red/blue fringing.
http://www.myastroshop.com.au/produc...sp?id=MAS-046A
That said you can try that focal length for $60+freight with the Celestron version that Mental4Astro is selling here:
http://www.iceinspace.com.au/forum/s...d.php?t=129263
If you end up getting something bigger/better for astro you will keep this for the ocean views.
A good quality Alt-Az mount for $289 in the Vixen Mini Port, but there are other choices around.
http://www.myastroshop.com.au/produc...p?id=MAS-033A3
Trev