In order to save money, instead of parking your car near or at bwi airport you might want to consider using one of the ground transportation bwi services.
The Baltimore airport ground transportation have lots of options:
- Shuttle or a van
- Car rental
The rail service is really cheap, it is something like $1.60 for a one way ticket, so you can easily check online the rail system, see if you have a cheap parking near the rail station and you just saved few dollars.
For a shuttle or a van you will need to read on Parking Preflight.us for the best review on bwi parking which has the best price and service. If you going to leave your can their you want to make sure you leave it in good hands.
Taxi can be a more difficult issue, not every company will drive you from your location to the airport. This option can be quite expensive as they charge you on your baggage too, we do not recommend this option.