I mean, every house seems to have one (Baratheon has two!), except for poor Martell.

Let's get on this already!

Martell hasn't featured in the HBO show, so HBO hasn't been touting Martell's house crest/artwork yet. Given that the new art sleeves are based of the HBO art... you'll have to wait at least a season!

you have a lot of customers in martell

martell sleeves and no more lannister playmats please

a red viper playmat,arianne too

~Martell is getting all the good cards already, they don't need swag on top of that !