Well, anywhere that is popular enough to need parking (e.g. downtown commercial) is going to be more expensive than a standard house lot in SillyValley. A 5000sqft lot is easily $1M and probably more so you're going to need $200/sqft just for land. The minimum size for a compact parking space is 8x16 and area usage isn't better than 50% in a parking lot so you're at 256sqft before you start building anything... that's $5k.