wide wheels and cheap dont really go in the same sentence.
but since you said modern would be ok
http://www.tamparacing.com/forums/nissan-sale/286638-18x8-18x10-5zigen-fn01r-c-wheels-hyper-black-potenza.html
these are cheaper used obviously but new im pretty sure they're cheaper than any custom 3piece or watanabe wheel, which would be your best options to fill out those flares right, honestly.
but, it'll be easier for you to find wide wheels since youre willing to go so big in diameter.