If you really don't have ten bucks for the expansion pack, but still want some more maps, well then i have just the thing for you!
http://planetbattlefield.gamespy.com/View.php?view=BF2Maps.List&game=3
this website has really good map downloads that are really confusing to download, but if you have enough patience, you will prevail!
If you ruin your game by modding it do NOT come complaining to me... thanks for particapating!