His value to the Saints this year is whatever player or players it would take to replace his production in the passing and running game as well as a 1st round pick. I'm sure that's not a price that anyone is willing to pay but this is likely Brees' last year and last real shot at a Super Bowl. You can't let your 2nd best offensive player go (and second best is really good when Mike Thomas is your best) without getting his replacement in return. His replacement just isn't available in this draft.
But, obviously if he decided to hold out, a trade becomes a much more attractive option.