Retail sales aren't doing great in the US - so there are sales all over. And September is still very low season in Florida. On your trip north to the Jacksonville area from Miami - I recommend the Town Center Mall (in Boca Raton):

http://www.simon.com/mall/default.aspx?ID=144

and the Gardens Mall (in Palm Beach Gardens):

http://www.thegardensmall.com/

Both are pretty close to I-95.

If you have more time - I'd take a detour to Worth Avenue in Palm Beach:

http://www.worth-avenue.com/

All of these - especially the last - may look somewhat pricey - but there are lots of 50-75% off sales these days. You might be able to get some pretty good bargains - even on Worth Avenue (which has been hit hard by the real estate recession and the Madoff scandal).

In/near Jacksonville - where I live (isn't much of anything between Palm Beach Gardens and the greater Jacksonville area) - I'd try the Avenues Mall:

http://www.simon.com/mall/default.aspx?ID=124

And the St. Johns Town Center:

http://www.simon.com/mall/default.aspx?id=857

I don't think most factory outlet places usually have particularly good deals - but you might take a look at Prime Outlets in St. Augustine - mentioned above - on your trip north (sales have been so lousy at Saks Fifth Avenue among other places that Saks Off Fifth and similar there have been carrying lots of very marked down high end names - as opposed to the "Made For Outlet" stuff).

And one exit north on I-95 from there is Tour Stop - which carries a huge selection of casual/golf clothing. Robyn