There is a strong used market in astronomy equipment, and I recommend Astromart to the individual interested in purchasing used. STAY AWAY FROM EBAY, unless you are already an experienced observer and know what questions to ask. Over the years I have purchased and later sold nearly all of my telescopes used on Astromart, as well as most of my eyepieces. Astromart charges a one time fee of $15 to sign up but it is well worth the security that the site provides in terms of limiting the scamming that takes place. In about 75 transactions through them, I have never had a fraudulent experience. Cloudy Nights also has a forum for buying and selling used gear, but I have never utilized this service.
Telescopes can be generally divided into three categories: Reflectors (those with mirrors), Refractors (those with lenses), and Catadioptric (those with both lenses and mirrors). That being said, within each of these categories numerous different designs of telescopes can be purchased, from the mass produced import scope to the one of a kind hand-crafted precision instrument. To the left is the first serious telescope I owned, a used Celestron Super C8+. Actually, this was the second telescope I owned but the first department store 60mm plastic scope does not count in my book. Isn't she a beauty? This was an 8 inch Schmidt Cassegrain Telescope (SCT) through which I observed for countless hours. She showed me the entire Messier catalog, several comets, and I made numerous sketches of the 2003 Mars apparition with her.
Several telescopes later (and wishing I still had that old Super C8+ in my arsenal) I currently have two refractors, and one Dobsonian Reflector. Each telescope has its strengths and limitations, and I choose which telescopes to utilize depending on what I am observing and where.
I am fortunate to own a Telescope Engineering Company 140mm triplet apochromatic refractor. This is a hand-crafted telescope, considered by many astronomers to be a world class instrument. While most amateur class telescopes are mass produced, TEC figures their own objective lenses by hand...in a small shop in Golden, Colorado. The TEC 140 rides atop either a Celestron German Equatorial Mount (left hand picture in the observatory), or atop a Discmounts DM-6 mount in the field (right hand picture).
At 5.5 inches of aperture, the TEC 140 is the workhorse instrument in the Lost Pleiad Observatory. It does an excellent job on planets, provides nice low power wide field views, and has just enough light gathering for some of the brighter deep sky objects. It is not a galaxy buster, but living close to town is not conducive to observing faint fuzzy details in galaxies. Under dark skies, however, I have seen very faint objects, and even Pluto.
Still under construction from here!!
SV90T
Dob
To observe the Sun's photosphere (the layer of of the sun visible in white light that often contains sunspots) I utilize a Herschel Wedge, also manufactured by Lunt Solar Systems. The wedge can be utilized in any refractor telescope (the bottom picture shows it inserted in the TEC 140).