The Favre effect is in full swing, and this short AP article gives some numbers to things I alluded to in my post below. The Vikes have sold 3,000 season ticket packs and about 10,000 single game tickets since the news broke yesterday. I just checked Vikings.com and was quoted a price of $741 as the price for the best available season tickets plus a $75 flat fee. Here's a couple of screen shots for those who might be interested.
If all season tickets were bought at this price, then the 3,000 sold would lead to $2,223,000 in additional season ticket revenue. The 10,000 single-game ticket sales, assuming a low-ball price of $40 per ticket gives an additional $400,000 in ticket revenue for a grand total of $2,623,000. Remember that the Vikes get to keep only 60% of this money, or $1,573,800 with the other 40% going to the visiting teams. Moreover, some of these tickets would have been bought even if Favre weren't going to play for the Vikes.
While this is a nice bump for the Vikes, they've got a long way to go to get the cash to pay his salary.