LOL could probably get a nice telescope setup that would do the same right?
Yes, you could get a telescope setup for well under
$1000 with similar if not greater magnification. The difference is simply going to be in the quality of the optics...telescope optics in the $1000 range don't tend to have the same precision as camera optics do...unless of course you're an experienced "glass pusher" where you can make your own mirrors with 1/10th wave accuracy. There are some models such as Takahashi and Vixen in the $10,000 that would probably come pretty darn close though. The thing with telescopes that is usually of greatest importance is aperture...in this case the actual size of the telescope. There is a saying amongst amature astronomers, "Apeture is king...bigger is better". Very simply a 12" telescope is going to "pull down more light" than a 8" telescope even at the same magnification. With that in mind, the precision of the optics isn't as much of a big deal as it is with terrestrial viewing...after all, if your looking at Saturn which is just 746 million miles away or the Orion Nebula (M42) which is roughly 1,300 light years away (1 light year = 5.87 trillion miles), having enough light become far more important than precision optics. In other words, that Canon lens for $99,000 and even the Sigma lens is without a doubt going to be considerably sharper than most amature level telescopes.
Now with that said, there are folks out there who can do some amazing things with cameras and telescopes from a terrestrial point of view. It's not difficult to attach most decent telescopes to an SLR or a DSLR...all you usually need is the right T-adapter (usually $15 from B&H). While I haven't gotten any results worth writing home about yet, I can even do this with my little $300 5in Orion Mak. There are a lot of people out there who are also getting into "Digi-scoping" (hooking up a digital camera to a spotting scope) who get some pretty amazing results. With the processing and sharpening tools out there today for programs like Photoshop and even "image stacking programs", the sharpness of telescope optics can be, to some degree, worked around. In other words, while yes, that $99,000 Canon lens would be really cool to have, there are other ways to get that kind of mag without having to take out a second mortgage LOL!.
Anyways...just the view on this issue from an amature astronomer