Your enthusiasm is wonderful but you have a bit to learn.
Originally Posted by scottyhoffo
Long lenses punish the least unsteadiness severely. To use even a 500 mm lens with any hope of getting the best it can give you'll need a very sturdy tripod.
I had severe sharpness problems with my 700/8 Questar 700 (the best mirror lens of its time, only the 750/6 Honeywell Lumetar came close) on a Bogen 3021 tripod. I borrowed two more Q700s from a friend, shot all three. Mine was slightly the best of the lot, and I localized my sharpness issues to the tripod. Now I use a Berlebach 8023, get adequate results consistently. Before the shootout I shot my Q700 against a 55/2.8 MicroNikkor at 1:2; shots at f/8 (KM, flash illumination) taken with the two lenses couldn't be told apart. It is a good lens, not cheap even nowadays. There's one on ebay now, the example shot in the listing is just terrible. A good 'un will do much better.
There's a law of nature to the effect that good long lenses are very expensive. The longer, the more so. The old Celestron 1250/8 wasn't at all bad, used to be relatively inexpensive. I have no idea what current prices are, if you really want a longer lens -- try out the 500/8 Nikkor, if you get one, first -- it is worth looking for. If you have the money and a strong back, look into apochromatic refracting telescopes.
Lenses to avoid? Inexpensive long zoom lenses are dreadful. The old 1000/11 Celestron C-90 -- I bought one in 1977 -- was absolutely horrible; there's a new version that I understand is much better.