If you are worried about weight and cost, why not go for an ali BP, harness for £130 (?) from Knackers and a Diver rite Classic wing for £130 from Go dive. What I have!!
More knowledgeable than me will no doubt jump in, but a single piece harness is required for DIR.
However, for more info look here
http://www.direxplorers.com/new-dir-...late-wing.html
HTH