It depends on your budget and what else you plan to do with the camera really. There is a lot of choice out there. Simple CMOS mono cameras with 1/3 size sensors typically used as guiders work ok with the SA, can be used for simple imaging of planets and brighter deep sky objects and can be bought from around £150-180. If you want a camera which can take spectra and images of faint objects or do photometry though then a camera with a larger size cooled sensor would be better and more versatile but are more expensive, typically ~£800 to the skies the limit. Good value can sometimes be found second hand though as people trade up. I have bought through Uk AstroBuySell for example.