For a bag, there are plenty of good choices listed above for custom, hand-made in the USA options. A lot of these companies (Seagull, R.E.Load, Blick's, Blaq Design, Bailey Works, a million more) make essentially the same bags (big, waterproof, durable) for about the same money ($150-250 for a really big size), so pick one with the buckling system/strap/other crap that you want. Most of them do hand-made custom orders, too, so just email or call and go with who you like. I have a bag from Blaq Designs that looks positively ridiculous, as it's almost completely covered in reflective tape, but that's what I asked for and they did it. I like to use it in the winter for a few reasons: more bike maneuverability with the weight strapped to my back, to keep some more heat in, and because I like having a square yard of reflective tape on my back when it's icy and snowy and dark outside.

For weather-resistant pants you can wear to work, if you want to drop seriously stupid money, both Outlier and Swrve (and I'm sure some other boutique outfits) make pants that would probably fit the bill. $100-200 is a lot to spend on pants though. I do have a pair of Swrve softshells and Outliers (yes, I'm willing to spend stupid money on possibly pointless things) - the Swrve softshells I wore almost every single day last winter, commuting 5-10 miles each way, the Outlier 4 Seasons I've managed to wear for weeks on end as well, in the spring and fall, and at this point both still look pretty brand new. They shed dirt, water, snow, salt, and road grit, and I can go straight from riding into a meeting at work. Some will mock (and rightfully so), but these stupid expensive pants do the trick for me.