A lot depends on how much money you have to spare and what kind of deal you can find on an extractor. In general I'll agree with Richard Taylor:
"A comb honey beekeeper really needs, in addition to his bees and the usual apiary equipment and tools, only one other thing, and that is a pocket knife. The day you go into producing extracted honey, on the other hand, you must begin to think not only of an extractor, which is a costly machine used only a relatively minute part of the year, but also of uncapping equipment, strainers, settling tanks, wax melters, bottle filling equipment, pails and utensils galore and endless things. Besides this you must have a place to store supers of combs, subject to damage by moths and rodents and, given the nature of beeswax, very subject to destruction by fire. And still more: You must begin to think in terms of a whole new building, namely, a honey house, suitably constructed, supplied with power, and equipped....
"All this seems obvious enough, and yet time after time I have seen novice beekeepers, as soon as they had built their apiaries up to a half dozen or so hives, begin to look around for an extractor. It is as if one were to establish a small garden by the kitchen door, and then at once begin looking for a tractor to till it with. Unless then, you have, or plan eventually to have, perhaps fifty or more colonies of bees, you should try to resist looking in bee catalogs at the extractors and other enchanting and tempting tools that are offered and instead look with renewed fondness at your little pocket knife, so symbolic of the simplicity that is the mark of every truly good life."
Basically I'd say you can do fine without an extractor for up to eight hives or more. And then, if I were buying new, I would not buy anything less than a 9/18 motorized. Extracting two frames or even four frames at a time is far to frustrating for me and a four frame extractor is usually not half the price of an 18 frame.
I held out for a 9/18 motorized. That was 2000 and I had been keeping bees for 26 years by then. But I stayed between 2 and 7 hives during that time.