Legal question- non LBC

[A666K@aol.com]

Sorry to bomb the list, but are there any lawyers out there who can tell me 
whether my putting down a deposit on a car legally bind the owner to sell it 
to me? Or can the owner just say "sorry I can sell it to someone else for 
more, here is your deposit back" I live in Maryland if that makes a 
difference, though any advice would be appreciated.
Thanks a bunch,
Avi