iPhone 4, iPhone 3GS $50 off at Radio Shack

Radio Shack is offering $50 in savings on the purchase of a new iPhone 4 or iPhone 3GS at their retail locations (i.e. offline only) until December 11. Better yet, if you have a good condition iPhone 3GS or iPhone 3G you want to trade in, they'll give you another $75 or $125 off respectively. Darren Murph of Engadget does the math on that:

you could walk in today, hand over your 3GS, and walk out with an iPhone 4 for $25 (plus activation fees)

Apparently they're eating the discount to gain some marketing attention for their wireless business. But chances are you don't care why -- they had you at cheap. Anyone taking them up on the offer?