I went to the Lambo forums and found out the cost of ownership of Gallardo is roughly $3-4 per mile. That's almost $30-40k a year if one drives 10-12k miles a year.
However, I also found out that to rent one in Los Angeles or San Diego is about $1200-1600 a day (100 miles per day free). Each additional mile cost about $3.60-5 a mile. So that comes out to a $12-16 a mile for the first set of miles. Each additional mile drops down to a cheaper rate. So best to drive more to get more value.
Sounds like it may be better for me to just rent it on the days I need it.