"Avida Dollars" was a derogatory nickname given to Salvador Dali by Andre Breton, the "leader" of the Surrealist movement. (Hint: it's an anagram of "Salvador Dali", and means, in an inter-linguistic mishmash of translation, "Greedy for dollars").
Breton came up with the name because of what he saw as Dali's commercial exploitation of his own art, which was (Breton thought) interfering with the artistic integrity of the Surrealist movement. Dali had been the poster child of Surrealism for a few years but as his own success and reputation grew he started to want to make a break with the movement, whose restrictions and rules for their members he felt to be a burden on the creative (and yes, commercial) freedom that he wanted.
He had already started to poke fun at the Surrealist sensibilities in rather childish ways - for instance, he had somehow come to the conclusion that Breton "did not like anuses" and hence had started to "sneak them in" to several of his paintings through his favourite device of concealed images. They had been having more and more open disagreements, but when Dali started to sell his "Surrealist objects" (a famous example being his lobster telephone) and paintings for large amounts of money to buyers mainly in the United States, Breton finalized the break with this nickname, which became famous.
Dali, however, did not seem to be in the slightest bit bothered, and his commercial endeavours, for which he did not apologize, did not prevent Avida Dollars from going on to produce some of the greatest paintings of the 20th (or any) century.