Been looking at them myself.
Looks as though they cost more to put together. The lowers are the same prices and you need some other things. Also seems like a lot of people destroy drill presses trying to mill with them. I have the more expensive Delta drill press sold at lowes and I think milling a lower would be hard on it.
Companies leave out different actions to get down to 80%. SOme leave out very easy to do things that must be done precisely and some leave out more grunt like work of removing lots of material.
I think I will go for a couple flats and a bending jig first. Seems much simpler and the from what I read the AKs are much more forgiving for small mistakes.