About the only commercially-made radius arms I would trust myself is Skyjacker.
James Duff makes a beefy arm too, though I've seen a couple of them crack in the notches right where the boxed section expands away from the piece of tubing they use (would probably want to add some gussets in that area if you use it hard).
As easy as it is to build arms yourself, I'd just go that route. Biggest thing is making sure you set the caster angle correct for your lift and frame bracket placement.