I've just got hold of a pair of antennae made by Markus from RCGroups, so I thought I would put them to the test.
It cost me $55.50 for the pair of them including delivery, which I think is a fair price for some handmade and tuned antennae. If you want to get hold of a set for yourself then you have to send Markus a PM through RCGroups and he'll get back to you pretty quick. As they are all built to your specific requirements, there is a bit of a delay in getting them and it took about 3 weeks from ordering to arrival.
You can choose from a number of different options such as the type and style of connector (SMA/RP-SMA or straight/right angle connector) length of feed cable and even exact frequency that you want it tuned to. At 5.8GHz this is very important as the performance is significantly effected if they are not well tuned.
When I opened them, the first thing I noticed was how well built they looked and the quality of the soldering on them. I also noticed that they look a bit fragile and you can easily bend the lobes, which would affect performance, so you have to take a bit more care in handling them than you would with the standard antennae that come with most transmitter/receiver packages.
To test these antennae, I used a basic 200mW 5.8GHz transmitter with the RC305 receiver, which I purchased from Hobbyking.
First I did a test with the standard antennae to get something to compare them with. I set up my receiver connected to my dvr and left it on the kitchen table. I then hit record and went for a walk down my street. On reviewing the footage I could see that the signal started to break up when I was about 30m from my house and was unusable by the time I had walked 70m.
I then fitted the 3 lobe Clover leaf (CL) antenna to the transmitter and the 4 lobe skew planar (SP) antenna to the rx receiver and repeated the same test. This time I had much better results and had a rock solid image for at least 60m before I started to get the odd breakup in the picture. The video was still usable out to 120m, but by this time I had run out of space to walk and had some houses between me. Still, this quick test was enough to convince me that these are going to be great for FPV on my multicopter.
Pros: Price, build quality, performance