To me it really depends on how powerful the cards are. Game-altering cards (like a Venka, Grim Smith, Tofu, Inevitable, ...) I would say could reasonably be sold for the highest price points, while less game-altering cards need lower price points. In general though I do think the prices were a tad high, so I voted for 30k/1.8k. I do believe that there will be more sales, and more overall revenue, at lower prices points that feel more accessible. However it'll be impossible to really compare given that the upcoming cards may be more or less desirable than the current 2.
In any case I will almost certainly buy all promo cards no matter what price point the company sets in order to support Splinterlands.