After two weeks of clearing backlog of Orders I have finally decided to regress to the simple Add to Cart buttons from PayPal, instead of the shopping cart add on i was using. This allows me to have available stock tracking, and when exhausted – to display out of stock message during the checkout on the PayPal website. It is not the best solution, but right now don’t have the time to play with various WP plugins or cart packages.
So to summarize – all kits will show as available on the Order page, but during checkout, if out of stock, you will not be able to purchase. This way i won’t have huge pile of back orders that ties me for a long time to process, but rather whatever i have prepared and ready to send – i will add as available quantity.
Thanks for understanding and support from everyone.