Not only is the paint expensive, but the prep is labor intensive. Primer with gold or silver undercoat, several coats of a semi-transparent topcoat, and then top it all off with clearcoats.
Not a particularly good choice for day to day street driving. You can't touch it up without it looking awful. The only advantage to the Smart is that you could remove and respray a panel individually. If your painter kept a record of number of coats and the exact paint used, you might pull off a match.
The price sounds really inexpensive, I don't know how it could be done for that - even on a car this small.