I've worked for two Fortune 50 companies that do not give out that information to their employees. It's certainly not available system-wide, and unless you legislated that into healthcare, it is unlikely to happen system-wide. Obamacare has not included that legislation.
While employers do look at the market, and tend to follow it in a general sense, the offer comes from an individual employer, and is an agreement between the individual and the company. Supply and demand works here, and in an economy like we have today, the employer has the ability to dictate the pay in many fields. If the employer did not, then we would not have minimum wage laws. The mere fact that we do shows that employers do have the ability to dictate wages in many (not all) instances.
It would not need collusion to have employers remove benefits without adding compensation. It only takes a few big players to do it, and then many more follow suit. Case in point, up until a few years ago, most large companies offered full pensions to employees, but look now, big Fortune 100 companies have managed to remove pension plans and replaced them with 401K plans that do not cost the employer as much, and have not raised salaries to address the compensation issue. A record high of 70 companies in the Fortune 100 provided only a 401K or similar type of retirement account to new hires in 2012, compared with 67 employers in 2011, and 63 employers in 2010. In 1998, 90 companies in the Fortune 100 sponsored a traditional or hybrid pension plan. This was done without collusion.
AT&T, Verizon, Caterpillar and Deere have already looked into dropping all healthcare plans - and without collusion between them. (AT&T, Verizon, others, thought about dropping health plans - May. 5, 2010).
I can tell you for a fact that one of those 4 has greatly reduced what they pay towards healthcare benefit already - without increasing compensation in any of their other benefits. I have first-hand knowledge of it.
Government single-payer - According to Canada's top think tank, and quite a few independent analysts, Canada's provinces are spending too much to keep the same benefits much longer. But we have nothing to be concerned about, because the US government is so efficient, right?
I am not against unhitching individual medical plans from employment. It's a good idea, and would empower individuals to change jobs with more ease.
What I don't see is how you can take away a method of compensation that employers value highly. The reason that they offer health plans is to get the employee to want to stay and work. Unless you legislate that they cannot offer a health plan, businesses will find loopholes to get around it, and the insurance companies will help them - it is cheaper for an insurance company to write a policy for 200,000 people than to write 200,000 individual plans.