Where is the best butcher in PDX?
The guy at the Saturday downtown market is Ben, and he should be able to hook you up with just about any part of the pig you are looking for. They do their cutting on Mon/Tue so if you are looking for something special for the weekend I would email him as early as possible. I know he has sold a couple full pigs to market goers and loves makeing customers happy.
His email is firstname.lastname@example.org, or www.nwpork.com
If you are looking for a pure butcher in town stick with Gartner's out by the airport. They are as old school as they come and do an amazing about of bussines.
If you just want pork bellies you can buy them all the time at just about any Asian grocery store, it's one of their regular cuts. We happen to go to An Dong. If you want the belly whole, and don't want to try to get it at an Asian grocery store, you can special order it from Carlton through Otto's, which gets deliveries once or twice/week.
If you want a whole hog, you have several options, all of them involving farmers, but be warned that most of the local processors do NOT leave the skin on, and most of the organs mysteriously disappear. There is one place that will do a "China pig" (this makes the ethnic Chinese in the house laugh) that leaves you with a clean and gutted pig (and they'll break it down into primals for an extra fee) but you never get the organs. Carlton is pretty much the only processor that can give you a pig with skin and organs (but they have to pass inspection by an USDA inspector so you might lose something).
Pastaworks does whole pigs from Carlton Farms. You will have to order it. Nice folks too.
There's also a stand at the Saturday farmer's market that does really good pork from a Willamette Valley growers co-op. You might stop by and chat with the very amiable guy about ordering things like pork belly and whole pigs. Warning, you'll buy some bacon no matter what happens, the guy always has some sizzling away and it's impossible to resist. And really, really good.
You might ask the pork stand at Hillsdale Farmers market about the whole pig or the belly. Also, I know that Three Square Grill sources some great local pork, but I forgot the name of the farm. I'm a fan of the butcher at Pastaworks on Hawthorne, but I think they may be affiliated with another larger name, like Viande.