It could be anywhere. It could happen at any time. I don't think that price will be the determining factor for these guys adopting Bitcoin but rather once there really is enough demand for them to accept it. How many of customers are asking for it?
Someone have to start it and then the others will follow.
I think that Google OR Microsoft will start first.
Microsoft already did about the XBOX payments, so Google will have to do something about it too.
So, I hope it's going to be soon.
About price - who knows and who can know? It can be any. From $250 to $2500.
Now, when it get adopted as a global payment (accepted worldwide), buyers (customers) will want it cheap, but by buying it in bulk/mass, price will go up, as it's logic.
On the other hand, we have miners who save coins and they will want to sell at good price, so when it starts to grow, many will sell some. So about the price, again - it can not be predicted anyhow.