It is a very labour intensive job IMHO, need to extend the beam inner mounts forward, then extend the outer arm mounts forward, make retainer points for the adjusters on both arm mounting points. Also (obviously) you have to be very accurate to make sure it all lines up nicely and travels in the correct arc, then buy/make 4x barrel adjusters, 4x locknuts, and buy 4x heavy duty 1/2" spherical bearing eye ends...Then powdercoat or paint to a high standard to finish it off.

Overall, a LOT of work, people have to make profit on it as most companys are not charitys!! Pretty good value IMHO, as you are paying for the time, materials, R&D and jig, and warranty of the product. If you have the skills to knock one up to a high, safe standard yourself, then go for it, but for most people it is easier to let someone do it for you who has done it before