Here is a link where you can get as much as $10.00 back from Federal on slugs purchased this fall.
This expires 31 DEC - so I apologize for posting it so late.
This is worth buying your slugs ahead of time now - for 2011 - just to get the rebates.
I use the 20 gauge with the Barnes Expander bullet and if you buy two boxes (my cost locally is $15 per box, so $30 total) you can get $10 back... that is a savings of 33% - good deal if you are gonna buy them anyway!
Hope this helps some of you....the link is below.