That sounds about right from what I've seen. I bought my Rogers ten years ago for £200 on the CTC forum. However, since then I've spent a lot more than that on it, not least because I put the drive wheel down a massive pot-hole and cracked an axle housing, so the upshot was a Trykit conversion to 2WD and indexed gears, plus a respray, from what had been a friction-geared OWD machine.
When I were a lad, my first club was the (sadly defunct) South Lancashire Road Club (which was actually based in East Cheshire, but never mind that). They reckoned to have more trikes than any club in the country at the time (late 70s), and held annual tricycle invitation runs. Which, of course, is why I formed the ambition to own one, one day.