In my experience, no, they don't bargain. From what I also understand, you cannot transfer your Lifetime to a new box. Sucks, I know. I just replaced my two old Series 2 with two Premieres and I had to think about it for a week or so before I went ahead and got Lifetime on both. I asked about any discounts or multi-purchase discounts (since I was going to add Lifetime to both new boxes) to no avail.
They didn't reduce the monthly to $12.95 until shortly after I purchased mine so the numbers I had were a little better, in terms of how long it takes to pay for itself. ha! way to rationalize, eh?