Paul Westerberg MerchandiseThis is a woefully short section of the site because there just isn't that much PW stuff to buy. Guy's not big on merchandise so if you own a PW t shirt of some kind already, considered yourself lucky.
At one point, there were several PW t-shirts for sale through JSR Direct but it seems those have all been snapped up. They do have some Mats t-shirts available though, for "Sorry Ma" and "Let It Be". You can find more Mats t-shirts at Burning Airlines.
Other than that, your best bet for shirts and posters is eBay (at least until the next tour...).