Not too long ago, I talked to a former Esprit owner at my company. He sold it because he had spent $12k in four years keeping it on the road. It was a 90 SE, just like mine. In the nine years I've had mine, maintenance has been maybe $2k, and 700 of that was tires. The rest is oil changes, cam belt change, chargecooler impeller, replacing a couple of fuel lines.
The difference? He was paying a shop to do everything, not a Lotus dealer, and obviously, they were charging him for the learning curve. I do the work myself, don't trust anyone locally. Wish I'd met that guy a year ago, I could have saved him a ton of money.
So, yes, if you pay someone else to fix everything, and they aren't an expert, it can be expensive. Do the little stuff yourself, and it doesn't cost much to keep one on the road.
As far as getting belt timing wrong, it's not that hard to get it right. Don't remove the belts until you have the engine in TDC 1. Lock the cams in place with a dowel rod. Take the old belts off. Slip the new belts on, being sure to keep them tight on the side that will be pulling the cams. After you've set tension, pull the plugs, rotate the engine with a long wrench on the crank pulley nut, and see if you feel any solid resistance. Two revolutions, you're back at TDC 1. Recheck timing marks. You're done. In retrospect, my 4 cyl is easier to work on than my Mercury Sable. Everything is on the bottom of that engine.
The Esprit is not idiot proof. Not when you're driving it or working on it. This isn't some Japanese econobox with neon lights and absurdly wide wheels. You actually have to know something about the vehicle.