If wheel bearing, then the cost will depend on whether the stub axle is damaged or not, form your description it sounds like a wheel bearing failure.
If stub axle is damaged then it's a new one, involving king pin strip down, if this the case then it might be worth thinking of replacing both at the same time with hardened chrome and new bushes, depending on how many miles the current ones have done and cash of course. You also need to inspect the brake disk carefully for damage, scoring. If you are lucky then you might get away with just a wheel bearing, I would replace the other side at the same time, I think a pair are about £60-70.
