past 24 months I've bought 6 10 packs and 2 5 packs (value ~ $720) and paid out $493. for about $20.54 a month.
However...going back that far I had as many as 6 teams... I have cut to 2 now, both of which are traditionally threats for S16 at least every season, so check again in 24 more months...plus I still have a half dozen seasons in my pool.