I buy the bearings only, from a bearing shop. I pop the seals out, wash em out, and regrease them with real grease. I have a press so I take the hubs apart, clean the rust out, and press the new bearing in. I refuse to pay someone else a ridiculous amount of money to do that for me. The bearings run about $80C to as little as $40C depending on application. I coat the splines with anti-seize.
To pop the seals out,damage-free, I took an old mini-screwdriver, and dressed the tip down to a knife point. I insert it into the inner side of the seal which is not attached to anything, and pop it right out. Some are tougher than others, and need to be straightened after removal.Take your time and make it perfect. The outer perimeter is sorta pressed in, but you can pop it right back in with your thumbs. I take out both sides, else it is impossible to properly get rid of the washer solvent.
You may have to remove one bearing from the hub to get a manufacture's pn to take to the bearing shop, because not all bearing shops have a cross-reference for automotive applications. Sometimes they have to match it up by measurement. If you don't have a press, it doesn't take much of a press to do the work. I would hire somebody local before I would buy a pre-assembled unit, for the price they demand. Course I live in a small town, and just about everybody knows me, and for the most part, they are kind to me.lol.