Certainly you can get away with speedlights (flashguns), and could probably put together a two-light location kit using, say, a couple of Yongnuo flashes, Cactus radio triggers and off-brand stands and umbrellas for a couple of hundred dollars or so. That will let you take the pictures you want—once every ten seconds or so while the batteries are still fresh.

"Strobist" lighting is a lot like using today's internet over a 1200 baud dial-up connection. It works, yes, but there's a lot of "oh, come on!" dialog in the air. It's not that you need to be able to tape down the shutter release on your 10fps pro camera and motor away like they do in the movies, but that there is a huge difference between waiting, say, two seconds between exposures and waiting 8–15 seconds (which is about 6–13 seconds beyond the point where the perfect pose or expression actually occurs, while you're stuck saying, "hold it... hold it..." to a model who is growing visibly more tense with every passing millisecond).

Indoors, where you can control the ambient lighting and bump the ISO up a bit if necessary, it's not a big problem. Outdoors, though, where you are in a battle with the sun, you can't really trade off flash power for recycling time. And that's what real location lighting buys you more than anything else—recycling time. You can bring down the recycling time of some speedlights with external battery packs (whether the makers' own or something like the Quantum Turbo), but most will overheat quickly, and either destroy themselves or kick in a thermal limiting circuit.

Whether the unit is a dedicated battery system (like the Profoto ProB or Elinchrom Ranger series) or an externally-powered studio system (ranging from low-powered Paul C. Buff AlienBees B400s with a Vagabond to... well, the sky's the limit, really), you'll get recycling times that mean you can take the shot when it presents itself, enough power to do the job without placing undue strain on the unit, and a relatively large number of flashes before you need to change batteries or call it a day. Consistently short recycling time, though, is the killer feature. You just don't get that from speedlights unless they're only providing fill.

If you're seriously budget-limited, or if this is just for hobby use and pro gear can't be justified,some of the older "potato masher" handle flashguns, like the Metz Cx45 or Sunpack 622 are powerful, recycle quickly and may turn up on the used market, but their newer equivalents are not significantly cheaper than location lighting units. You may also want to watch for older Norman or Lumidyne units. But if you're stuck with ordinary speedlights, understand that they're not going to be more than something that makes the shot possible—they won't be something you'd want to use all day, every day if outdoor beauty/glamour/portraiture is going to be more than an occasional bit of spice.