I've been looking in to lifting my explorer, as mentioned, suspension lifts are practically non existent. We have 2 options and both are very expensive. Super lift and trail master if I remember correctly, I think the trail master was discontinued though, but still available some places online.
The 4 inch suspension lift is like $1600, and you need new custom CV shafts, those were another $500 or so. The site I was pricing this out on didn't specify if it was a matching set, or per axle, but I assumed a set.
My explorer is fairly rusty so no way I was going to throw $2100 at it for a lift.