With the 3rd party sample instruments crossgrades, I think all you have to is to get it registered in your NI account.  I don't even have the Estey Reed Organ installed at the moment, but it shows up as available in my NI products.
 
Then when I look at my Kontakt crossgrade eligibility, NI says the Estey Reed gets it done! 
"As an owner of Soniccouture - Estey Reed Organ you qualify to install and activate this version."
 
https://www.native-instru...cing/crossgrade-offer/

Fleer
AFAIK there’s still the free Sennheiser DrumMic’a that’ll allow you to crossgrade.

This indeed worked!  I did need to download and install the Sennheiser program, then I was able to take advantage of the cross-grade to the full version of Kontakt.  Even though the Sennheiser website is in German, the layout is very standard for these types of website.  Meaning you can probably guess your way through the questions and options!  Plus i got a slightly different drum program to try out.  

Your browser should have a translate feature...

I was doing the initial sign up on my phone, as my computer wasn’t available. And I know a little German, so I didn’t even bother with seeing if I had a web site translator program for Safari on my iPhone. But your suggestion is noted.

Be careful what third party libraries you buy for Kontakt player as they may not be recognised as eligible for cross grade. There seems to be a defined list on the NI site. None of the ones mentioned here so far appear to be on that list. But then again I could be wrong. There does not seem to be any easy way to get Kontakt 5 full version cheaply.  By the time you add the cost of the third party library to the cross grade price it seems to add to close to just buying it outright.
 
 

The samplemodeling in my post above was confirmed by NI site as stated, so I don't follow?
 
Do you have a link to this list?

here is a link to the third party products using kontakt 5/player that makes one eligible for the crossgrade price:
 
https://www.native-instru...arty-sample-libraries/
 
Maybe not the easiest list to go through as I dont see a 'search' function.  I did find Sennheiser's DrumMic'A on the list, and indeed when I went through the checkout line, before committing to payment, there was a green check mark and a confirmatory message saying I was eligible.  I will try to post a pic.
 

 
 
This will come up after you put Kontakt in the cart and as you start the checkout procedure, but before you have to pay.  So this would be a way to confirm crossgrade coverage for something registered on NI's site. 
 
It appears right now that the only way to checkout eligibility for a third party product before you would purchase it, is to check through the listing above.  

Jeff Evans
Be careful what third party libraries you buy for Kontakt player as they may not be recognised as eligible for cross grade. There seems to be a defined list on the NI site. None of the ones mentioned here so far appear to be on that list. But then again I could be wrong. There does not seem to be any easy way to get Kontakt 5 full version cheaply.  By the time you add the cost of the third party library to the cross grade price it seems to add to close to just buying it outright.

True, but there have been a couple of FREE libraries that make one eligible for crossgrade pricing. 
 
If you actually bought a 3rd party library to use with Kontakt Player, I hope that was something actually needed, not just for the crossgrade to the full version. 

I have actually been looking at third party libraries and that is very true. Most of them I am not interested in. I either have something already very similar or just don't want it. So I am hoping there is another way perhaps. If they just halved the price of the full version I would probably jump. It is $600 AU here so as you can see that is quite a chunk.

Jeff Evans
I have actually been looking at third party libraries and that is very true. Most of them I am not interested in. I either have something already very similar or just don't want it. So I am hoping there is another way perhaps. If they just halved the price of the full version I would probably jump. It is $600 AU here so as you can see that is quite a chunk.

Well it is $124.50USD with the 50% off and the crossgrade from an eligible library.  I have the Soniccouture Estey Reed Organ, which was a giveaway a while back, and that works. 
 
The ongoing free deal seems to be Sennheiser's DrumMic'A.  The webpage is in German, but if you can register that for free you get the Kontakt crossgrade.
https://www.native-instru...r-drumica-free.198219/
 
http://sennheiser.us/drummica.html
 
Hint: The Google Translate browser plugin should get you started...
https://chrome.google.com/webstore/detail/google-translate/aapbdbdomjkkjkaonfhkkikfgjllcleb