I'm afraid so and many of them (resisting the chance to say "all") are quite nasty.

I actually went down to Sovereign Cars after selling the Aero 8 to look at a Cobra. The fit and finish on the Dax and AK was quite good.
This was the one I went down to look at. The problem was I didn't fit in it - if you think the S1 Aero 8 is narrow, these are much tighter across the cabin. The DAX seemed a little wider and the width even seemed to vary slightly from car to car.
The one that was quite impressive was the ABSOLUTE PERFORMANCE built cars -
link . The only downside is they get quite expensive and imho, I'd rather have a new/nearly new Aero 8 for the same money.