Bear in mind that many journals do not accept advertisements, especially those published by scientific societies. The Physical Review and Physical Review Letters are examples of this. They are published by the American Physical Society in several volumes each month. An entire month's worth of the set (Phys Rev A, B15, B30, C, D15, D30, E and PRL) would easily make a two foot stack on your desk. PR and PRL do not accept ads, so the production costs have to come from somewhere.

Of course, all of PR and PRL are currently available on line as well as in print. The on-line subscriptions are substantially less than the dead tree version. My PRL subscription comes to about $30 in addition to my APS dues and is well worth it.

That being said, there are some journals that try to run a profit. APS just concluded a nasty lawsuit with one of them (World Scientific's journals I believe) over a study they did on the influence (based on citations) of various journals against their cost. World Scientific took exception and sued. APS won, but it took a while.

APS and AIP do have a lot of free on-line content. And I believe they are making some articles in PRL available for free. The journal world is still making the transition to the electronic age, so some teething pains are to be expected.

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"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

This isn't right. This isn't even wrong. - Wolfgang Pauli