Just a thought here, if you have trouble finding one that meets all the criteria and doesn't break the bank, I personally would put the steel gears on the less important list, you really shouldn't be exerting much pressure on the gears (probably doing it wrong if you are) and the gears are typically inexpensive and replaceable, If you're concerned about them breaking or wearing out (honestly, how long will that take??) Then just buy a spare set and stash them for when you need them.
The only reason I raise this point is because it seems like loads of entry level stuffers fit the other criteria, but have plastic gears...
And the only reason I hate plastic tubes is that most of them are tapered, if you were to end up with straight/non-tapered tubes you'd probably be fine.
But I could be missing something here, hopefully someone else will correct me if I've overlooked a critical area of concern.
One last thing I forgot to mention is that having 2 speeds on the stuffer is really nice if you plan on doing a lot of sausage, if you're only making smaller batches and only occasionally, then a single speed will work fine