BYU has firm numbers for what their cost of attendance is:

Room and Board: $7,330
Books and Supplies: $1,008
Personal Expenses: $1,960
Transportation: $2520
Total: $12,818

Someone posted yesterday that BYU is already paying scholarship football players $900 per month. I have no idea if this is 8 months out of the year during fall and winter semester or year-round. Assuming it's for 8 months then BYU is already paying $7200 per year. To make up the full cost of attendance, BYU would have to pay an additional $5,618 per scholarship player. With 85 football scholarships, the total would be around $477,530. Doesn't seem like a ton or something that would price out BYU. Even if BYU did what Texas did and added $5000 to use their likeness, that's another $425,000 per year. All total, less than a million bucks.

Based on these numbers I have no idea where Texas came up with the $6 million figure to do full cost of attendance. One possibility is that they added in all the scholarship athletes from all sports, both men's and women's. That still doesn't come close to the $6M figure though. Here's a list of the scholarship limits for Womens sports: There are 14 volleyball scholarships, 15 WBB scholarships, 14 Swimming scholarships, 12 softball scholarships, 14 soccer scholarships, 12 Rugby scholarships, 6 golf scholarships, 18 track/CC scholarships. I don't know the scholarship limits for gymnastics. All told, it's barely over 100 scholarships, so it would be a similar number to the football impact: about $1 million.

There are significantly fewer men's non-football scholarships than there are women's scholarships due to Title IX. All told, if BYU added the full cost of attendance for all scholarship athletes, it looks like the cost would be less than $3M. BYU operates it athletic department at about a $5M surplus each year. While it would cut most of the surplus out, it's well within BYU's budget to keep up with Texas and anybody else they want to.