Giving away "expensive" kit is an investment for a start if they give a reviewer a 3k amplifier its cost them £700 max they can write off to tax as R&D and it would cost more than that to buy that amount of advert coverageit's a very incestuous industry, kit is often never returned, do you honestly think RG paid for his £30k+ wiring loom, besides even the honest ones still have commercial considerations to take into account, re advertising.
also the stuff they keep they sell on I have been offered some nice kit in the past by a couple of reviewers