This is the sort of thing.
Is anyone interested in forming a “syndicate” and refilling a load of these in one go?
There are firms that do it. They put them into a pressure chamber and the gas leaks in past the seal, but can’t get back out again because of the way the seal is made. If you can process say 20-30 struts in one go, it is very cheap. I recall charges like €200 for the whole job lot.
For things like door struts this is a no-brainer because if it doesn’t work too well, it doesn’t matter. But reportedly it does work.
Different struts require different pressures, so if the group contributes a diverse bunch of struts each would need to be repressurized separately. It might be worth understanding if the vendor can determine the correct pressure from part number or inspection, or whether the buyer needs to specify the pressure.
Indeed, but a lot of them seem to be 400N or 600N. The pressure would depend on the diameter which seems to be fairly standard (or one of several).
I guess the interest would be limited since most European pilots are in the hands of a CAMO.
Hundreds of gas struts found here, link does not work precisely, look for Gasdruckdämpfer category on the left page:
Having been through the gas strut sourcing game, I found that one of my planes has a gas strut with particular end fittings, force and stroke that is only available from one vendor on the other side of the world at great expense – something like $400 IIRC. At least it’s available somewhere, but I have a spare and repressurizing it would make a lot of sense. They seem to go 5-10 years.
OK Vic here’s a common one – The TB20GT door strut
Like the nose landing gear struts (2) this one is 600N.
I have some background here and a part of the issue is that they went from 400N to 600N and had to change the dimensions in the process. One could have gassed up the 400N ones to do 600N but the Q is how long would they last, and anyway the supporting bracket was marginal for the stress and had to be replaced. You will see the nose gear struts (replaced anually) have a Porsche P/N but frankly they are cheap enough for probably nobody to bother.
I am sure one could buy a strut on which one could modify the fittings but the purpose of my post was to explore whether there is any call for forming a “regassing club” 
I am building up a stock of the old nose gear struts. I donated a few to one mechanic; I am fairly sure he didn’t regass them. Most of them are still good after a few years…
gas strut 400 N 256 mm
The PDF from ACE company shows a lot of types from page 138 , different ends, but higher prices from € 40.- plus :
That ACE company is a good find; they seems to have a huge range. I will get some measurements when I am back at work.
I recall refills costing about €200 so obviously you want to do a load in one go. The seals are not changed; I don’t think they can be because of the way the material is bent over at the end. These “auto trade” struts are not serviceable.
