Authorized retailer BuyDig has a couple of great deals on already discounted and popular Tamron lenses. There is currently a $100 mail-in rebate on both lenses.
Use the coupon code RUSHMORE to save an extra $130 instantly on the 70-200mm f/2.8 VC G2 and an extra $200 on the 150-600mm f/5-6.3 VC G2.
Be advised, that after you use the coupon code, you will not see the discount until the confirmation page. You'll see the notice at the top of your cart.
This is the lowest price seen on these lenses and I assume they'll expire on Sunday night at 11:59PM EST.
Download the mail-in rebate form here.