The obvious wikipedia articles...
...don't have this info. I'm not sure why; there must be reliable estimates somewhere, but not even tables at Astronautix have the flyaway costs: http://www.astronautix.com/articles/costhing.htm
The only estimate I can think of right now is that Soyuz Rocket's flyaway cost must be something less than $50 million, because that's currently the widely reported price to take a ride on Soyuz to the ISS for a few days.
For Proton Rocket, I expect it to be higher not only because it launches 20 tons, but also because it uses those hypergolic propellants that are very dangerous and require a lot of extra safety on the ground, costing money.
Can anyone help us find reliable estimates for flyaway costs for these 2 rockets?
To be clear: Flyaway cost is the cost of manufacturing the rocket plus servicing and doing whatever else is necessary to launch it. It does NOT include payload costs, so don't add the cost of Soyuz spaceship to Soyuz rocket.