1/
Ian perhaps consider going wider to the whole aviation community via a crowd funding organisation. Us members can help make that fund request "go viral" posting it to all the existing aviation media be it online FB, Instagram print media orgs etc and to flying organisations such as AOPA, SAAA, RAAus etc. That's a lot of people I am sure don't know about the site.
2/
With some of the funds place ads in aviation media to gain new members, site awareness benefits etc.
3/
Charge members an annual fee equal to a magazine subscription or part thereof. ($20?)
Offer a 3 month trial fee of $5.
4/
See if you can become a spot/ click fee agent for sales on all/any aviation shops, products (EFB memberships) /organisation and list links on your site. Don't know how hard this is to set up.
I am happy to contribute a membership fee or donation.
Keep your chin up and keep networking out to that big ocean of abundance, it usually bring rewards and support as you can see from this thread. .
Regards