As far as the cost goes, I think that's cheap for Lotus ! The hardware might be cheap and I doubt the programming is any great difference between what you get in some phone/tablet apps, but Lotus have always charged top dollar for their aftermarket parts.
Having said that, my Elise had a problem in it's early days which involved Lotus changing the Stack unit (rev counter/speedo/temp/fuel/warning lights) and I'm sure I remember being told that the part cost £1000, and that was back in Jan 2000. £1500 ? cheap as chips !
Brian