SHA 256 mining needs a big investment. The best Scrypt mining devices are the latest AMD cards, like R9 280x, or R9 290
Asrock build a motherboard, that can handle up to 6 cards at the same time.
http://www.tomshardware.com/news/asrock-bitcoing-mining-motherboards,25092.html

The ultimate Scrypt mining rig would be that motherboard, and 6x R9 290 card.