I've been happy with the senbazuru paper packages I've been getting on Amazon.

As mentioned, most are not actually 3 inch.

The tuttle packages are the most expensive and has patterns on one side and a solid contrasting color on the reverse. It's good for models, but not if you want continuity of color for modules that have more than 30 or 40 pieces. I've purchased this box twice now, I had so much fun with the patterns when making the Tomoko Fuse seastar and the Bascetta Star.

I bought this Aitoh packet last month, though I haven't built them yet, they're a light geometric pattern on one side and white on the other. It's not textured on one side like some better Japanese papers.

Toyo also makes a packet of solid colors, I've not used the small papers, but the 6" are decent though the variety of colors is a little weird.

I got this box of Aitoh harmony colors (32 of each pattern/color combo) and made all of them into 30 piece sonobes. That looked like this with a package of Japan Bargain washi paper (more textured white side and smooth pattern side).