I just got my Curve on Amazon as an upgrade for FREE! I was charged $44.99, but that was for the first month of service. As I already pay for a Blackberry plan, the $44.99 will be applied as a credit.
BTW, the new minutes plan I signed up for through Amazon gives me 100 more minutes a month for $35 less a month. That's a savings of $410 a year, along with a free Curve. On my Amazon Prime, I also got free 2nd day shipping.