You'd think so. I'll take a crack it this, keeping in mind that I can't personally recall the last time I flew a kite.

The only (but seemingly excellent) commercial visual distress signal kite I found on the market, the Sky-Alert Parafoil Rescue Kite, retails for $53 US, and seems targeted at the marine market.

It requires 5 knots (6 mph) of wind to get aloft, and 8 knots (9 mph) wind to loft a strobe. It is a 28"x38" parafoil with 12 feet of streamers, likely based on this patent.

I'm pretty sure I could buy a cheaper kite - so why has this one has survived on the market since at least 2002 , likely since 1986?

A few points in its favor that I can see:

• It is USCG certified as meeting the USCG requirement to carry a distress flag, which its target customers require anyway, and seem to go for about $10, so there's sort of a $10 discount here.
  
• As a parafoil (non-rigid frame), no assembly required, it likely packs compactly, and is tough
  
• It apparently has the lift to hoist an honest-to-god USCG compliant strobe (which is the light I'd want up there)
• It is marked with the standard USCG distress markings, so there is some hope that the message will get across.
• The target market (especially sailboat owners) are likely to be out in windy enough conditions to loft a kite.
• Will fly when wet.

{ Late update: Non-emergency Kayak Kites in this class go for $45-$49 with no USCG certification and no emergency markings, so I think the Sky-Alert Parafoil Rescue Kite is a bargain price when you consider the effective $10 USCG credit and the fact you get emergency markings included. On top of that, soft kites of this class seem to be recommended as the easiest to fly and easiest to setup/takedown (essentially, none required), so it seems like a good fit.}

The choice of balloon vs. kite depends on the wind speed. No wind, no kite. In the local foothills I tend to hike in, there's rarely enough wind for a kite. On the other hand, as the wind picks up, balloons look like a poorer and poorer choice. The British Jungle Marker Helikite, as a hybrid balloon/kite, spans a 0-25 mph wind range, having the advantage of living in both worlds.

The Balloon and Kite Antennas site looks to be a fount of information about using balloons and kites to loft equipment from an expert facile with both ( he apparently habitually leaves his kite/balloon lofted antenna 50 metres in the air unattended overnight). Here's is a guide to what he recommends as a function of wind and weather, which transitions from balloons through hybrids to pure kites as wind speed heads up to 45 mph: Recommended lifting units vs. wind speed

One proven approach is to have both balloon and kite handy, and switch off as wind condition change. For hoisting the antenna of the German/British/American emergency dinghy radios of WWII, the kit was equipped with a box kite for winds above 13 mph, and two 36" diameter balloons and two hydrogen generators, for when the wind was under that. See this great page: Gibson Girl Part I: Air-Sea Rescue

I did find this: 1869 patent mentioning lofting a light with a kite as a distress signal