I thought it might be useful to see if we can get some collection of best buys in the expensive Market place. It can also be a good idea to collect ideas and web sites to purchase products that Is a lot easier to get in the US.
Here's a few ideas for starters...
If you need similar testing kits to those recommended by this forum it's very difficult to locate the same products here. Send a pm to Teapot for a reasonably priced and similar product
Very expensive from some swimming pool websites. If you know the size. I recommend this engineering company called Bearing Station. Rings cost around a pound with a pound delivery.