What you need for decent astrophotography is an aplanic version of the R-C scope. Either buy at a high price or build one at a much lower price is your choices.
When you build the scope, make it dedicated to photography and you will have fewer comprimises to make to the design.
You will find tho that the really high costs will be in the camera system that you will need to buy (or again, build) to take the photos with CCD cameras. Plan on a filterwheel at the minimum and a shutter as a very viable option to the camera. The shutter will allow for things like a plane traversing through the field of view to not affect the image you are taking.
Many astro clubs have mirrormaking groups or gurus that can assist you in doing a decent sized scope the first pass around.
I'm in the San Diego area and am the guru for the SDAA club and am presently working with one guy that is working on a R-C and just got another guy that is interested in doing a Lurie-Houghton scope which will be interesting to do.