Reddit reviews 1 Month Subscription: EVE Online [Instant Access]

There ya go https://www.amazon.com/Month-Subscription-Online-Instant-Access/dp/B00GDHD3LW

Don't use steam.

Amazon is currently having a 10% off promotion for game time.

Two things come to mind, I believe the issue you're having is the 2nd:

1. The address you're using must be a US one.
   
   
2. If you're trying to upgrade a trial account you have to purchase a starter pack and not simply gametime.

What about Amazon? http://www.amazon.com/Month-Subscription-Online-Instant-Access/dp/B00GDHD3LW/ref=cm_cr_pr_product_top

I can use billing address of my uncle, should it redeem on european account?

Subscriptions usually don't go on sale, as there's a near-permanent 30% off sale on the 1-year sub. Of course that mandates wanting a full year, and having that much $ upfront...

Occasionally Amazon will have a sale, but you can't rely on that usually.