Sylamando
Putting in all the Ravnica duals isn't very cost efficient and not incredibly effective. You want to take two damage every turn to drop a land? You won't really have the option of dropping them tapped if you're playing slivers.
as for $... i doont really care too much... i spent 280$ last week alone on cards. and anyways that everything in this deck costs 2 or more... i dont have to take 2 damage on the first turn. (and + there good cards aso if i dont get them for this deck il put them in another deck"s")it is an option that is ecncially better then throwing in the cards like city of brass and other cards simeler like that sense i would die faster takeing 1 damage everytime i tap it for mana. ive alao notised that if these where mostley basic lands it isnt very effective. i usaly die from not haveing the right mana. the lands ravnica lands prevent that.
so the only other thought i can think up is finding the perfect balence between basic and non basic(or ways to get out the basic lands out)witch will take many games with the deck to try to find.