> $ 2.75 = $58.30
> $ 3.25 = $68.90
> $ 4.25 = $90.09

It's important to remember that those are the prices for the first edition.
Obviously, you should never pay more than $90 for one today. :-)

I often use the Inflation Calculator that Barb mentioned to look up
current values of dollar amounts mentioned in Twain's and other
historical writings. They are sometimes astonishing. For example, in an
1877 letter to Thomas Nast proposing that they do a joint tour, with Nast
drawing pictures while Twain lectured, Twain estimated that the profits
from a four a half month tour would be from $60,000 to $75,000. In 2006
dollars, that would be $1,096,304 to $1,370,380.

On the other question, Larry Marshburne, "The NAACP and Mark
Twain," Mark Twain Journal 36:1 (Spring 1998): 2-7, might be useful. It
reviews mentions of Twain and his works that appeared in its publication
The Crisis from 1910 to the 1990s. It also quotes an article that
appeared in The Crisis in May 1936 in response to it (The Crisis) being
banned from schools in Washington, D.C., because the word "nigger"
frequently appeared in its pages. He did not find opposition to
Huckleberry Finn until 1985 after a campaign was begun urging that
"Afro-Americans should take the lead in halting the widespread use of
the word 'nigger' in American media and expurgate this term from our
society. To accomplish this, enlightened black citizens must make a
concerted effort to challenge this issue on all fronts." The first attack on
Huckleberry Finn appeared in the magazine a few months later.

Jim Zwick