Just returning to this topic with a mini review.
I found a UK source and ordered an arm.
Initial impressions: very well molded, no obvious flaws and rubber parts looked, errrr, well like rubber. All felt nice and stiff as much as I could tell by hand.
Fit: A doddle to change, went straight into place. Took less than an hour and this was my first one.
Conclusion: Solved my troublesome rattle and notice no difference to handling. Seems durable enough as it's now been on the car 10 months. Considering the price compare to an OEM part it's difficult to argue against using them.