Cmon guys let's be real. Has Sprint ever released a phone for more than $600 before discounts? I doubt it'd cost more than that, regardless of what's inside.
The new iPhone cost definitely helps things too
I'd guess $199 after rebates for the Diamond and ~$50 more for the Pro, or maybe $249 for the Diamond (same opening price for the Touch and new Treo) and ~$50 more for the Pro.