It's simply question of $$ vs. draft picks and which you'd rather save.
If you'd rather save the money or want to spend on other FAs, then yes, the draft has many talented centers who could be had for cheap. But it would cost a draft pick that could otherwise go to other areas of need.
If you'd rather save draft picks and don't mind breaking the bank a little, Brown is the favored option.
Personally I'm ok with spending on Brown as long as we can still afford a safety (Bell or Wilson - max. 4M/yr?), a 2nd tier cornerback (Bodden/Bartell - 3M/yr?), and Coles (5M/yr?).