Hi Dave,
I have a Kango SDS (hammer drilling only) which is a fabulous drill which I use for most masonry drilling; an enormous and quite heavy B&Q SDS which does drilling, hammer drilling, or hammer only which is useful for some DIY jobs; and an ordinary B&Q two speed drill for woodwork and drill stand use. Got all three for under £200.
If you were to buy only an SDS drill you would need an additional chuck, which is fitted via an adaptor into the SDS chuck, to take ordinary drills. This might make the physical length of the drill too long and unwieldly for many jobs and it would probably be far too long for drill stand work.
Quite good drills seem to be available for far less than £200 and I think you really need more than one to suit different types of work.
If you decide to buy an ordinary drill as well as the SDS, my advice would be to stay away from keyless chucks. In my experience they do not grip well enough and can easily ruin drill bits. Change it for a keyed one.
Hope this helps
Paul