NRL and AFL 2010 clearance guerneys/jerseys are reduced to $50 as of next week, but lower prices start earlier for season pass members. Went to my closest store this morning and there was a huge collection, had to stop myself from buying every Geelong one available :)
If you're friendly enough and get a nice guy behind the counter, they'll often put numbers on there for free too. (though I dunno if that's just the boobs factor)
NFL —> AFL in title.
edit: pfft, negged for pointing out a typo. what's the world coming to.