Tamron 90mm Macro

Hi everybody,

After much research, I think I have decided to go with the Tamron 90mm macro f/2.8. The Sigma 105mm would be another choice but from what I have read so far, Tamron is pretty darn sharp. Lens will be used for 50% macro and 50% portraits.

Here is my dillemma:

I want to take advantage of the 25% live.com cashback by buying on ebay. Unfortunately, I cannot find a single authorized Tamron reseller sellling this lens on ebay. (Tamron is also offering a $90 mail in rebate only good if bought from authorized dealer).

I am wary about buying this through an unauthorized dealer.

So I have two options:

Buy it from B&H for $460 less $90 mail in = Net cost of $370

or

Buy it on ebay for $400 less 25% cashback = Net cost of $300

Any suggestions will be greatly appreciated.

-Shaba