He will be 28 in May of 2012, so basically the start of next season. Meaning he could want to play (at least in contract terms) for up to 12 more years. He obviously won't get or ask for that. But asking for 8 yrs wouldn't be out of the question.
He is making 15.5 Mil this year. He is perenial all-star and lately an mvp candidate. He also plays a premium pay position of 1st base.
2011 Top 1B salaries:
Texieria 23.1 mil
Helton 20.2 mil
Cabrera 20 mil
Howard 20 mil
Fielder 15.5 mil
Morneau 15 mil
Pujols 14.5 mil
Pujols wants near the 30 mil mark, and im sure Prince will want to be in the top 3. So the start of the conversation is at 20 million. That's a 160 mil for the 8 yr contract.
Worse yet for the Brewers, Ryan Braun only makes 4.2 Million this year. How would they pay both of them?