As a fellow Lotus fan, I know exactly where you're coming from. And which is why you need to go buy yourself an MR2.
Pick an early one up for £1200-£1500, strip everything out of it, put a decent seat in it with a pair of harnesses and you're done. It will give you 80% of the Lotus for 20% of the cost, and be considerably more reliable. For cheap MR fun, there's really no better place to look. You can easily disconnect the ABS and power steering too, if you want it to be even more Lotus-lite. Plus, performance bits are a lot cheaper too...