I think you mean prevailing wage and plenty of articles have show that companies have a variety of dodges they use to pay H-1Bs less than the prevailing wage, In addition, their mere presence creates a downward pressure on wages throughout the industry.
I am not sure I know the answer to your question. I was surprised to see the numbers of projected graduates exceed the potential jobs count. Our industry's constant message is that it cannot find enough engineers to fill the positions. Maybe in future it is going to change?
In my line of work, in the last few years we were able to fill several positions with well qualified recent graduates, without resorting ot H1B program.We also have an intern program with local engineering school. From what I see, the qualification and motivation of the interns is quite high.
Being a past H1B holder myself, I want to assure you that it is by no means a "low cost" source of employees: it is quite a hassle for a company to jump through legal hoops to sponsor a visa, and they have to show that they are going to pay a prevailing wage. However, it is harder for H1B holders to leave the job, which makes them more stable employee base.