Not sure if BMW lease deals are regional or not, but I'm in NC and took advantage of the Thanksgiving weekend lease specials. I selected a 24 month one payment lease - essentially prepaying for the entire lease up front. The money factor was very attractive - 1.02% APR with several other discounts included. In my state there is a 3% tax on automobiles - which was added to the lease payments, along with something that seems to be unique to the southeast - a dealer "documentation fee" which for my dealership is $598. This fee is added to all vehicle sales regardless of the sale price - it's a fixed charge to cover dealer "costs" for processing paperwork. It's a complete ripoff but legal in my state as long as it's applied to all cars.
Anyway, when I first inquired about leasing my i3 Giga non Rex i3, with technology package, heated seats, rapid charger, and Andesite paint the MSRP was $48,100. My initial lease quote (from late May) was over $700/month with $2,500 down for a three year lease - a price level that didn't interest me at all. The price I negotiated for an all in one time payment two weeks ago is $9,200 - that includes NC tax, implied dealer documentation fee and all other costs. That's the equivalent of just under $385/month - quite a difference.
The lease is a "walk-away" lease - at the end of the lease I'm finished - the lease includes the termination charge and everything else. Given my experience I think you can do better than the quote you've been given, but I do know that BMW provided and extra $2,000 discount incentive for the Thanksgiving promotion. You may/may not get that discount. If not, it would raise your two year lease by $85/month or so. On the other hand you likely won't be hit with a $600 documentation charge - offsetting costs somewhat.
If I decided to pay monthly two year lease payments, and a $2,500 down payment (which includes the first month payment and the termination costs) my monthly payments would have been about $60 higher. The lease money factor was higher on the two year monthly lease option (I don't remember exactly, but it was 2.5-3%), which resulted in the higher cost.
I had leased a Nissan Leaf for $209/month with $1,500 down for two years on a regional promotion. My negotiated i3 lease "all in costs" are about $110/month higher than the Leaf. The MSRP difference between the two cars was over $11,000 - making the BMW i3 lease a far better financial proposition versus the Leaf. And in terms of the car the i3 is a far better car in every way than the Leaf - with the exception of total passenger carrying (5 versus 4) and cargo room (somewhat greater in the Leaf - but not as well shaped as the i3).
Finally - I looked at the residual values for the two year lease and they are high - making leasing an even better deal. I figured that with a $48,100 cost for my car, as optioned, subtracting the full $7,500 federal tax credit, my adjusted base price is $40,600. Subtracting out the dealer's $598 documentation fee, and the 3% NC "road use" tax, the actual BMW calculated costs including depreciation and implied interest on the i3 is under $8,400. That suggests that the residual value of the car after two years will be $32,200 (adjusting for interest carry).
I highly doubt that a range limited i3 BEV will seem like a good value at that price at the end of 2016, especially with the new EVs coming out from Tesla and others. For that reason alone I decided that leasing was my best option - I think you'll find that the math suggests the same for most people.
If you can get a good lease deal on the 2014 i3 I strongly recommend it. The rates are nearly half of what they were before and the car is without competition at this price point. In fact, the lease on the i3 is less than on many 3 series cars with lower MSRPs. Ask the dealer to provide the "money factor" used to determine lease payments. Multiply that figure by 2400 to convert it to an APR rate equivalent. You should be able to get the equivalent of 3% or less. This has a pretty big impact on your monthly lease rate, with residual value the most critical. The residual on my car was $30,320 (not adjusted for interest carry). That figure seems very aggressive, and makes for a good lease deal.
The last issue to consider is the federal tax credit. While most expect it to continue for several more years, there is always the possibility that it won't be extended. If that's the case the lease costs, and purchase costs, will rise significantly, another reason why I decided to lease now. This shouldn't be a problem for 2015, but may be beyond that.
Good luck on whatever you decide - you'll enjoy the car.