AVERAGE: In 2000, the average value of an MLB team was $238 million. In 2019, the average value is $1.735 billion. This is an increase of $1.4097 billion (728%).
Even cherry picking what's probably the lowest valued teams (Tampa, Oakland, Pittsburgh, Cinci)... They all show pretty nice valuation increases:
https://www.statista.com/statistics/194639/mlb-franchise-value-of-the-tampa-bay-rays-since-2006/
https://www.statista.com/statistics/194631/mlb-franchise-value-of-the-pittsburgh-pirates-since-2006/
https://www.statista.com/statistics/194629/mlb-franchise-value-of-the-oakland-athletics-since-2006/
https://www.statista.com/statistics/194607/mlb-franchise-value-of-the-cincinnati-reds-since-2006/
For the big boys:
https://www.statista.com/statistics/194628/mlb-franchise-value-of-the-new-york-yankees-since-2006/
https://www.statista.com/statistics/194621/mlb-franchise-value-of-the-los-angeles-dodgers-since-2006/
And Toronto
https://www.statista.com/statistics/194642/mlb-franchise-value-of-the-toronto-blue-jays-since-2006/