Hi Tay, and
The most important bit of advice I can give you for starting astrophotography is to choose a good mount. I think the consensus is that an HEQ5 is the starting point to get good tracking without headaches. If you go for a lesser mount, like an EQ5 - like I did, then you'll find it frustrating as even when everything is setup just right you'll still struggle to get consistant tracking. I can guarantee that you'll want to upgrade sooner rather than later and it'll end up costing you more than if you had just spent a bit extra in the beginning.
When it comes to a scope you have a few choices but the two most common are going to be either an 8" newtonian reflector or an ED80 refractor. I personally started with an ED80, to use with my 5DmkII, and it was great. The focal length is not too long so, with good polar alignment, you can get up to about 2 minute unguided exposures. Once you want to take longer exposures or you want a longer focal length scope then you'll need to buy an autoguider setup. The consists of a small camera and a small guide scope, plus you'll need software to control the guiding and this means you'll be bringing your laptop wherever you set up.
So a basic setup consisting of an ED80, or an 8" newt, and an HEQ5 is going to be above your budget. I think the cheapest version of this - an 8" newt on an HEQ5 is about $2000 and an HEQ5 on its own is about $1500. If you can only afford $1500 now, and assuming you're pretty serious about getting into astrophotography, you could buy just the mount now, and take long exposure images with your 5D and lenses on the HEQ5 for now and then buy a scope when you can afford it.
Anyway that's what I would do with the hindsight I have from going through it already
