The mixer attachment types are OK for smaller amounts, but you need to pitch your choice of mincer at the volume you're going to use, or you just end up wasting money on the thing. We always do a session on choice of machinery at our pork butchery weekends for this very reason.
My own recommendations for more than making a few pounds here and there are, at the lower end of volume, a Porkert manual mincer - you can shift a hell of a lot through that. Then you have the Tre Spade types, basically a scaled-down commercial machine. Then the big jobs. We paid £1500 for ours second-hand from Windsor Food Machinery (superb service), it will mince 20kg of pork in about 38 seconds on the 10mm plate. It's a Sirman no. 32, which my missus has named Stephen Fry, because it's a huge great mincer.