I am a fellow KC dweller, and have had a hard time finding anywhere to pick up quality stationery. Know of anywhere local to find it?
If you are specifically looking for paper for letter-writing, I would recommend the Paper Source on the Plaza. They carry an assortment of options from companies like Rifle Paper and Chronicle Books. Paper Source also carries paper and notecards in small packets in lots of colors with matching envelopes.
If you are looking for notebooks and other stationery goods, a lot of boutiques and small shops in places like Brookside, Crestwood and Prairie Village often have a table with products. Hammerpress in the Crossroads stocks a variety of desk products like Field Notes and they stock a few Kaweco Sport ALs and a few other writing tools as well as their fabulous cards, postcards, posters and calendars.
The Nelson-Atkins Museum Store has some lovely products as well. The museum is always free admission so popping by just to scout out the shop is an option. And lunch in the Rozzell Court is quite a pleasant affair.
For ink and fountain pens, the Pen Place in Crown Center is your best option. They have a wide variety of pen brands, from inexpensive like Retro 51, Lamy and Kaweco to much more expensive options like Waterman, Montblanc and Pelikan. They also stock lots of ink (Noodler’s, Private Reserve, Mont Blanc, Pelikan Edelstein and many more). The nice thing is that you can see a swab of the inks before you purchase it but their costs tend to be a bit more than online retailers. If you go in informed and take into consideration shipping costs versus must-have-it-now, it might be worth a visit.
Let me know if you have any other sources for paper, ink, pens or office supplies in the KC area or if I left anything out. Hope this helps.