He said his side had paid $105,000 for "actual documentation from two witnesses" and made a $200,000 deposit for a videotape they had yet to receive.
The hearing went on hiatus two weeks ago so the arbitrator, Fredric Horowitz, could tend to other matters, It resumed Wednesday.
Rodriguez was one of 14 players suspended in connection with the Biogenesis scandal and is the only one who appealed his suspension.
Rodriguez, 38, is fifth on MLB's list of all-time home run leaders, just six behind Willie Mays. He would make $25 million in 2014, if his suspension is overturned. If his suspension is upheld, he won't be eligible to return until 49 games into the 2015 season.
He has filed suit against MLB and retiring Commisioner Bud Selig, alleging they "engaged in tortuous and egregious conduct with one and only one goal ... to destroy the reputation and career of Alex Rodriguez."
Tacopina said in August that Rodriguez was a consultant to Biogenenis.
"Clearly there was a relationship -- a consulting relationship," Tacopina said. "I mean, Biogenesis, that lab has consulted with many professional athletes. Not every single one of those athletes has been accused of or found guilty of using illegal substances."
He said Monday that Rodriguez had "absolutely not" taken steroids recently and MLB doesn't have any evidence that he had.
However, Rodriguez has said he used drugs in the past.
In 2009, Rodriguez admitted to taking performance-enhancing drugs while a shortstop for the Texas Rangers between 2001 and 2003. He won the first of his MVP awards in 2003.
He was traded to the New York Yankees before the 2004 season. He played 44 games this year, batting an underwhelming .244 with seven home runs after spending the first part of the season on the disabled list.