Tyre repair kits
 

Can anybody suggest a supplier where you get a lot more valves, caps, plugs etc than you normally do on the standard tyre repair kits you get etc.
I want to pad out my existing kit with some decent quality bits....

Just buy more of it?
All that stuff is available at any car parts store.

There is the ARB tyre repair kit which seems very sufficient to me. But also expensive, there are much cheaper alternatives with more seals/plugs. But having a kit with 50 or 60 plugs is maybe useful if you are running a garage :P
And I don't like the plastic boxes, they take up a lot of space for just a few tools and plugs which you can throw into any toolbox.

I must say I always carry this stuff but never used it. As soon as I have replaced a flat tyre with my spare, first priority is finding a tyre shop in next village or town, as they fix it better than with a plug. Also safer.

You can pick up Safety Seal plugs off eBay; they're excellent. The ARB plugs are a bit thick in my experience, although the kit itself is excellent. The Extreme Outback Ultimate Puncture Repair Kit has everything you'd need for a lifetime of repairs. Just avoid the cheezy plastic-handled plug inserters from auto parts stores; you need solid metal handles.

This comes from repairing tires in the field and also teaching several dozen classes on tire repair.