The title says is all. We'll be in Amsterdam 2 weeks and have decided museumkart works best for us. I'll assume Rijks and Van Gogh museums are the worst places to purchase it. Thanks!
It's tricky because of new rules for the Museumkaart. You can only use it a five museums, and where you purchase it counts as one of the five. I'd work out exactly which five museums you will be visiting Then try a smaller museum for your purchase, such as the Dutch Resistance Museum or the Amsterdam Museum. However, if you need to buy it at a major museum instead, I'd choose the Rijks--which seems to have faster ticket lines--rather than the Van Gogh.
Here is an unofficial website that has more information in English about the Museumkaart: http://dutchmuseums.com/museumcard.php
We were there at 12 pm about 3 weeks. No lines to buy museum card. Our timed entry was 1 pm but she said to go right in. Only small crowds. Good cafe for a light lunch.
I haven’t been there since 2014, but if you go to the Rijksmuseum, OUTSIDE THE MUSEUM, about halfway between that and Van Gogh museum is a building that looks like a news stand. Sort of gets overlooked by everyone heading to the museums, but they sell museum tickets and passes. If you get there first thing there’s no one really around.
Assuming you stay at the same accommodation, with a two weeks' stay, you can get yourself a personalised Museumkaart, without the limitation of 5 museum visits. For that you need to register your card and load up a passport photo, using this page on their website. It will be delivered at your adress within a week.
Easy places to get the museum card are: The New Church on Dam Square, The hidden church in the attic called Onze Lieve Heer op Solder. But don't use the card at either of those places as they are cheap to get in, like 10 euros, so not a good use of your 5 uses. If you know anyone here get them to buy you one online before you come, and have it posted to their address for you. It only takes a few days to arrive. To buy one for you they will need a photo of you (digital) and a Dutch bank account and address.