Oxymizer cannula

Under the heading of

or any other suggestions

I would suggest getting the O2D2 demand regulator and then you can use the much cheaper plain cannulas.

The plain ones can also be washed out (in alcohol) though I would not rely on this across different people

I have two oxygen writeups on my website.

Transair stock the SkyOx stuff, but it may be cheaper to order direct from the US.
If you do order from say Aircraft Spruce then specify USPS for the cheapest shipping on small packages.