Spending per month, in 2005 dollars:
Reagan I: 249,900
Reagan II: 162,500
GHW Bush: 91,800
Clinton I: 269,000
Clinton II: 123,000
Tenpas and McCann emphasize not the differences among presidents but patterns over time within presidencies:
bq. We find that presidents do not vary significantly in the average amount spent per month on polls. There are, however, two recurring patterns of variation within presidential administrations: Presidents tend to spend significantly more on internal polling during the most intense months of a presidential reelection campaign; and polling expenditures increase over the course of each presidential term. These findings suggest that there are common forces (e.g., elections, natural decline in support) that have driven all presidents since Ford to poll.
Their data on George W. Bush only cover the first two years of his first term. They do not report his total spending during this time, but over these 24 months, Bush also spent more on polling as time went on — a pattern similar to previous presidents.