What cables to use in the Dell r610 with the perc 6/i

So I bought my r610 as a barebones system so it didn't come with a raid controller or cpus/drives. I have gotten everything I need, except backplane cables. Some came with my perc 6/i but the cables are for another similar server (they are not the right length). The only cables I have found are $100 which I find outrageous. Is there somewhere else I should look/ is there a certain type of cable for this server and a certain length? Thanks!