Unless they are in almost perfect condition or there is something otherwise unique about it larger value bills like this have little value above face yet. While they may have additional value in 20 or 30 years, I would guess that inflation will eat up any additional collector's value by then.
These were printed in huge quantities and while most have or will be destroyed in favor of the new bills I suspect there are going to be plenty to satisfy the collector's market.
Personally I might save a pristine 30 year old $20 I came across but it would have to be a lot older for me to save a $100 note.