When purchasing a new phone, is it imperative to deal with the wireless company directly? I am considering switching from Sprint to Verizon, and am interested in the LG VX10. Radio Shack has a trade-in deal where you can get the phone for $69.99 after mail-in rebates. It retails at Verizon for $149.99 with no rebates available. Seems like a no-brainer (same product for lower price), but I've been advised by a few people (not including the Verizon sales reps!) to only deal with the wireless company. Any opinions?