it should be also depends on how what coins you are going to miner , what kind of miner you will purchase .
the G(M)hash / power is important for the person who contribute electricity and space .
For scrypt :  http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1312.R1.TR9.TRC1.A0.H0.Xsc.TRS2&_nkw=scrypt+mining+contract&ghostText=&_sacat=0

For Sha256:  http://www.ebay.com/sch/i.html?_odkw=scrypt+mining+contract&_from=R40&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=sha256+mining+contract&_sacat=0