The scope and camera are secondary when starting out. Get a stable equatorial tracking mount - you will need one to image deep space objects and you can start by using your existing camera and lenses on it. The HEQ5 is the lowest cost mount that is generally accepted as a serious imaging mount. Look for a used one if the cost is off-putting, but don't bother messing around with anything less unless you want to be continually battling to get results. Sorry, but that really is the entry point, unless you are happy to restrict your imaging to wide fields, where a polarie or similar will do the job.
good luck. Ray
maybe read this
http://www.danlessmann.com/Articles/AstroMistakes.htm
quote from the article: "In your own efforts, please, please, please start with the mount and make it a quality equatorial mount. Anything less and you'll be disappointed and frustrated as building a house on a shaky foundation will never work no matter how nice the house."