If you are planning make some returns, then you have to invest a lot more than 15k into it.
Considering the difficulty level of litecoin, with 2000KH/s mining power you would be making around $700 first month( Based on current price). To achieve that 2000 KH/s in the most cost effective way is to get 3 radeon 7950s. These things are almost sold out everywhere. It would cost 70K+ combined. On top of it add an Asrock board, a cheap processor , 4gigs of RAM, 1000 Watts PSU, Hard disc if required or else a thumb drive, riser cables, fans, and a frame.