Here is the cost scales and previews as the guild unlocks more areas to customize on your cloaks.

The initial level of customization only lets you change the background color and Heraldry Icon. It can be opened at guild level 15 and cost 5 plat every time you want to change anything.
The next level opens at guild level 30 and lets you modify the trim pattern and color in addition to heraldry and background color. It can be opened at guild level 30 and costs 20 plat to change anything.
The final level opens at guild level 60 and lets you modify the background pattern as well as all the previous modifications. It can be opened at guild level 60 and costs 50 plat to change anything.
(Click thumbnails for preview)

Emblems(Required Guild level 15)

Edgesb(Required Guild Level 30)

Patternsb(Required Guild Level 60)