@IndianBill
To be honest, the price below 2000 won't be anywhere as good as those over the 2000 threshold because of 2k/10% twitter rule.
I'm going to give you my opinion on prices for these, but this is just my opinion, you may get more, or less depending on who your trying to sell to.
500 $10.00
1000 $25.00
2000 $50.00
Now, over 2000 you will be able to charge more because people looking to buy anything over 2000 have already run into the 2000 following limit and are waiting to get their followers up to the same level so they can start following using the 10% ratio.
Targeted would of course be valued much higher (probably close to double)