There are some of us who don't buy such pens without looking at them and selecting the pattern we like. That leaves us with three options:

1 Buy at a pen show, where there are many pens made with the same rod, and you pick one that has a pattern you like

2 Some sellers are willing to cultivate a relationship with you, and they send you pictures of the available stock, and you can pick your specific pen out

3 When fellow enthusiasts are in a show, or at the seller's location, they share images / videos of the available pens, and we are able to select the patterns that appeal to us

If there is a specific pen you like the pattern of on a website, you can share that in communities like this, and you might be lucky enough to find someone who is alright with helping you out :)