Are you currently leasing a 2011, 2012 or 2013 Nissan LEAF? If so, then perhaps Nissan Motor Acceptance Corporation (NMAC - the leasing/financing arm of Nissan) has a deal that's right for you.
Running through the end of June, NMAC is offering current 2012 and 2013 LEAF lessees $5,000 towards the purchase of their leased LEAFs. Basically, NMAC will knock $5,000 of the buy-out price of the lease LEAF, thus making it extremely affordable to outright buy.
The deal on 2011s isn't nearly as sweet, but lessees of that model year can still get $1,500 towards purchasing their leased LEAFs.
It should be noted that this deal is through NMAC, so you don't even have to visit a dealer to take advantage of this deal. Simply contact NMAC and a representative will walk you through the process.