Home charging not available, crazy to buy?

I live in a flat I own and don't have a driveway. I could get a charger that goes accross the road if Im able to secure the spot outside my house but this will be on/off quite inconvenient. Is it crazy to be getting a m3? There's a paid charging spot about 20 meters away and im 20 mins from a supercharger. Are the paid roadside chargers crazy expensive? I dont commute so will be about 3-miles a day to the gym and them big weekend trips I guess I can plan a supercharger stop en-route. Any advice would be amazing!!