Thanks for the email! Great find!
It doesn't appear however that this offer is from Sprint, but rather from a sprint reseller (grouplotto).
They offer the 1500 minute plan (250 anytime + 1250 off peak) for $45 / mo. whereas Sprint sells the same plan for $35 / mo. They also require a 2 year contract which typically would give you an ala cart option from Sprint (such as long distance) or a $100 credit. Additionally Sprint is offering a $30 rebate on single phone purchases.
Since this plan includes long distance and considering that the startac is now $150 from sprint, we are only talking about a $120 savings on equipment ($150 - $30 rebate) for which you must pay an extra $10 / mo. for 2 years = net loss of $120.
I didn't factor in the activation fee ($30) that you can often talk them out of. This is a very interesting find but I don't think it's a wise choise. This is of course only my opinion.
The best deal from Sprint is to be part of a large group such as UPS - they offer a 20% discount for UPS employees and a 15% discount for Ingersoll-Rand employees. When you sign up under one of those groups you get the applicable discount off any available plan as well as free activation and the phone is fedex'd to your door for free as well. If you sign an 'advantage agreement' you get $50 equipment credit for each 1 year period OR you can apply it toward an ala cart option (such as 500 cell-to-cell minutes). I am only mentioning this as a point of reference!