If that is so then why did the producers spend a rumored quarter of a million dollars for the use of a genuine Beatles song this season? (and it wasn't even one of their hits)
AMC is the one who doesn't want to spend money on Mad Men... the Mad Men producers are fine with spending money to make quality TV. AMC tried to cut their budget (like AMC has done with other shows), tried to force more product placement, and tried to have less episodes and shorter episodes to sell more commercial spots.
The Mad Men producers fought for a bigger budget, more shows, longer shows, and less product placement.
So you're asking the wrong question here... Mad Men producers wanted an authentic song from the times to set a mood and were willing to spend money in their budget to make the show seem accurate. AMC, I'm sure, would not have wanted to spend that money.