If you find the cost of the phone to be too expensive from any source, you can add a second line (or use a second line that has a dumb phone attached too it), buy the phone against the second line at the discounted price, and then immediately transfer the new phone to your primary line. You might be stuck paying for the second line for 2 yrs because of the obligation, but discounted price plus paying for the line is cheaper than full price. Also you may get lucky and find a sympathetic CSR that can cancel the second line at no extra cost to you...
I recently did this so I can get an s4, but so far I'm still stuck with the second line.