I've used the HP units and they aren't too bad. 50 pages at a time is 100 sides at at time if it is a auto-duplexor. Your average paper back is under 200 sides so two groups of less than 50 and you're done.
Besides, anything more than that and you're a freakin' pirate right?
This past weekend I got myself a new set of magazine shears. Home Depot had some Titanium Nitride Fiskars on sale. Today I used them. They cut the spine off Infoworld like a hot knife through butter. You don't even have to pull out the staples!