I go by /~Owls values, but generally prefer doing item-for-item trades (especially for higher-value items), but if there's something I really want, I may offer GBCs/custom :)
I also have sale sections for GBCs at the very end of this list, meaning some items are 2 items = 1 GBC/4 items = 1 GBC (or item equivalent), as well as a FREE section (no limit per person, except if I don't have enough gift boxes).
26th Anniversary Kougra Black Friday Gift Box Mystery Capsule x20
Styling Studio Supplies x2
NC Upcycle Fortune Cookie x1
Trendsetter Mystery Capsule II x2
Trendsetter Mystery Capsule III x2
May Fever Premium Mini Capsule x3
Styling Studio Prismatic Brush x3
Lab Ray Fortune Cookie x1
Training Fortune Cookie x2
Peaches and Dreams Premium Mini Mystery Capsule x3
Dyeworks Hue Brew Potion x5
2 items for 1 Gift Box Capsule
4 items for 1 GBC
FREE! No limit (besides # of gift boxes I have)
Not actively looking for these at the moment, but if the opportunity arises... :)