Eugene Volokh, of the Volokh Conspiracy, has a piece on the recent decision by the Supreme Court striking down Randall v. Sorrel.
The reason that the court struck down the law here--which, among other things, would have limited a candidate's total spending for Vermont state representative races to $2,000 for both the primary election and general election put together--is not that money is speech. Rather, it's that restrictions on spending money to speak are restrictions on speech, and "money is speech" is, I think, a misleading way of expressing this claim.
It's fun to read some of the analogies Eugene comes up with to illustrate why a restriction on campaign spending is a restriction on speech.
Would we say "money is abortion"? I doubt it, but a law that banned the spending of money would surely be a serious restriction on abortion rights (whether or not you think that the court was right to recognize such rights). A law that capped the spending of money for abortions at a small amount, far smaller than abortions often cost, would likewise be a burden on abortion rights, and dismissing this argument as "it is quite wrong to equate money and abortion" would be unsound.
Likewise, we wouldn't say "money is education," or "money is lawyering." Yet a law that capped private-school tuitions at $2,000 (not just limited the amount of government-provided scholarships, but capped private spending by parents for tuition) would be a serious, likely unconstitutional, burden on the right to educate one's child at a private school. Likewise, a law that barred wealthy defendants from spending more than $20,000--or even $200,000--for assistance of counsel would violate the Sixth Amendment. Even if for some reason you thought that these laws should be upheld, the response that "it is quite wrong to equate money and [education/lawyering]" would be an unsound response.