White Plains is a teeny airport. It's been a good while since I flew out of there (it was 2001-02,) but I think there were 4-6 gates then. There's not much room for expansion (as it's an airport smooshed where there really shouldn't be one,) so it's doubtful it's grown much, if at all.
Parking is limited to a single, small parking garage, is very limited, and is very expensive. You're risking IF there is parking when you get there. I've never heard of anyone being turned away, but then, anyone I knew who flew out of there has either been dropped off or had a car service.
I think I just read a poster say that there's a hotel in Armonk (I'm not sure which one, but last I knew there were only a few there anyhow) that does a park and fly deal. Not sure how you'd get from the hotel to HPN, though. They're not particularly close.
Depending on how much luggage you're bringing -- and how you feel about public transport -- your best bet might be to take Metro-North to the White Plains train station (or a nearby stop... as the White Plains stop may not be the closest) and take a taxi from there.
I love the airport; the upside of it being so small is that you don't have to worry about being AS early for your flight as one of the larger area airports. Be aware, though, that there's no place to buy food past security... the terminal area is pretty small. And if there's bad weather and flights get backed up, it gets crowded fast lol.
If the cost savings is substantial, it's probably worth it to try to figure out alt transportation arrangements. If not... you may find it's more trouble than it's worth.
One other thought... check Stewart (Newburgh, NY or SWF). It's probably similar distance from you in CT and the parking situation there is much better.
Good luck!
