The last time the Saints had an opportunity to draft that high was 2017. They wanted Mahomes, and were going to to take him but the Chiefs moved up and the rest is history. The was roughly 8 years ago. There's no telling when we'll be picking 9 again, if a QB is there that you love....you take him or move up for him. Nobody remembers how much the Chiefs payed to move up to 8...they just know they currently have Mahomes and are perennial SB contenders.
No price is too large to pay if you think a guy can solidify you for the next 10 years at the most position in football.