I am considering acquiring a folding kayak or even a inflatable one. They all seem to be missing a rudder. Any hope of finding one?

I just looked on line and saw a bunch of sites for rudders for folding kayaks.
Do a search “rudders for folding kayaks”.
I can’t visualize how they come apart and go together, but they evidently have them

Feathercraft, which is no longer in business, had models with rudders. Should be available used.

Trak, which is in business, has an interesting method where you adjust the boat’s left/right trim as you paddle using hydraulic jacks to make the whole boat act like a rudder. Not as quick and easy as a foot operated rudder, but good for long crossings with side winds.

Keep in mind, rudders are meant to make a kayak go straight. A common issue is when a boat is moving forward and has winds coming from the side, the boat will try to turn into the wind. In this case, a rudder (or skeg) is used to offset this to allow you to go straight.

When you want to change the direction of the boat, it is much more efficiently done using paddle strokes.

There are many models with drop down skegs, particularly amongst the inflatables. I’ve owned 6 different folders and only one, a Feathercraft K-1, was rudder equipped. Honestly, I never used it and eventually removed it as a nuisance, though it was such a well designed rudder that I know many people bought the FC unit even for their hardshell boats. So probably less a criticism of the rudder itself than the fact that I am not a paddler who likes them. I did find that the strap-on rubber skeg that Feathercraft supplied with some models and as an accessory for others was a definite aid in tracking and correcting windcocking.

Pakboat has an add on rudder for their XT and Quest models, if you are determined to have one. I owned an XT in the past and currently have a Quest and have not felt they needed a rudder.