I might try a $50 one and report back. I had really bad luck with cheep ones on jeeps and ford. but I think the jeeps are too small to start with the discovery like a better size for the vehicle so the cheap ones might last.
Not sure what the factory removal procedure is. I soak down the hub with penetrating oil (PB Blaster) the day before. To remove; I back off the bolts about 1/4 inch and then tap the bolt heads with a hammer, working my way around to keep it coming off square (and undamaged). I've seen them chiseled off, thus messing up the mating surfaces. In the front I put anti-seize on the mating surfaces, to make it easy remove the next time. And blue lock-tite on the bolts. I know this wasn't asked, but I've seen some crazy ways of getting these things off.
As noted by others, if you swap those hubs, clean out the tubes and make sure it's coated in some way to prevent rust and seizing in the future. Even if it's clean now, the vehicle is old, and it'll be on the verge of needing some attention in that spot, as the mating surfaces have a fairly high area.
When assemblies such as those are highly resistant to conventional removal methods, there are essentially unlimited other ways to get it done quickly. Just use your brain, a bit of muscle if that's your way, and don't break a sweat. As long as you get an even pull, you'll be fine.
As with almost every other undercarriage part, soak it the night before. I generally use CLP, but you'll rarely get people to ditch their favorite penetrating lube.