The Congressional Budget Office estimates that the House plan to prevent cuts to doctors' Medicare reimbursement rates would cost $210 billion over 10 years, according to a just released analysis.
The big price tag is no surprise and was the main reason House Democrats introduced the so-called "doc fix" legislation separately from their $1.2 trillion reform bill—Dems were trying to keep the cost of the reform bill as close to President Obama's target of $900 billion as possible.
I've heard the argument that removing this provision from the larger health-care legislation, as House Democrats did, isn't really a cheat (or at least not one that matters) because the doctor fix doesn't have anything to do with the rest of what's in the health-care reform bills. That's strictly true, but I also think it was in the original House bill for a reason: It's the offering Democrats are using to buy the support of doctors, who don't want to see their Medicare reimbursements cut. By putting it in the original bill, I think Democrats signaled pretty clearly that they think the two are related—but now that CBO-certified deficit neutrality has become their major concern, they're trying to back away.