I have written software to analyse the prices that cars go on that site, and I cannot find anywhere cheaper. Seriously, you will not get an MX-5 for under £1,500 and those will be ropey. The 1.8 Z3's can go for reasonable prices, and I would be tempted by one but there are a lot fewer and that engine is not rated well. There a few early 2000's CLKs going every week for well under a grand. The Barchetta is FWD, which puts me off a bit, and you see few of them. I am not sure what the Opel GT was in the UK, I assumed it was the
Vauxhall VX220 but wiki says not. Anyway, I am sure there are not lots coming up cheap.