If you want to actually see the Polar Cap on Mars,  the Red Eye of Jupiter, or Gas Cloud Structures in Nebulas;  you have to get a Diffraction Limited set of Optics.  While all the major manufacturers of telescopes claim to build diffraction limited systems, most of them simply don't perform to specs by the time you get them into the field.  In addition, they recommend against you tuning the optics in many of the Schmidt Cassegranians and Refractors.  So you spend $3500.00 for a telescope with fuzzy images.  What a drag!

80% of the cost of this scope was devoted to these critical components:

Primary Mirror                    Galaxy Optics 18" f 4.5 parabolic with 96% coating
Diagonal "turning" Mirror     Galaxy Optics 3.1" elliptical flat
Eyepieces                            Nagler 3mm Radian, Wow!
Focusser                             NGF2  2" with 1.25" adapter

Some Builders insist on grinding their own mirrors and flats, and that's fine if you know how, and you have the time, equipment, ...etc.  If you make any sort of a living wage, it is better to spend your time working overtime for the money to buy good optics, than to outfit a shop and learn how to finish optics to within 60 nm like John Hudeck at Galaxy Optics.  Making a Focusser as good as an NGF would cost you far more in time and materials than $170.00.  As for the Nagler Radian Eyepiece, I can't begin to advise you because the thick lens equations at work here are actually Rocket Science.