In reply to The Lemming:
Horses for courses of course. A decently robust slider is at least 250, but 350 upwards really and for that wedge, and you are looking for a variety of shots, it is in Ronin S gimbal territory, an astro photography motorised tracker, various lenses, macro, ultra wide, a chunk of another body for shooting different angles of the same scene. There is probably more scope and variety in the other items I mentioned apart from an astro tracker, but for short exposure astro there isn't another way I am aware of, whereas as you say its easy to mimic a slider in post. Or to cut a long story short with £350 I'd buy one of the others first with a slider coming down the list quite a way.
Post edited at 22:52