Personally I would go for something aftermarket like BBS. Genuine OEM wheels cost a fortune new and reps are a complete waste of money, especially diamond cut ones. Also, OEM wheels won't give you that new wheel feeling for very long, whereas a nice set of BBS's will always look special.
I presume you have 17" Monzas at the moment, so if there is a usable amount of tread on them, store them away to put back on the car when you sell it, or use them for winter tyres.