Yeah, my last bid for re-building worked out to about $6 per SF, and in the last few years, depending on region, I think prices could be $8-9 SF, depending on liner, amount of drainage, sand cost (that white sand can cost up to $130 per ton) etc. To spend $5,000,000 on bunkers would be impossible (over 500,000 sf when small bunkers like those, typically placed could be as low as 50,000 SF and probably not over 100,000 SF on any traditional course.
And these days, the $5Mil for greens, tees and bunkers sounds about right.