I think investing in some patches/badges and finding interestingly coloured skirts, skinnies, and loose boy pants will make DIYing an amekaji outfit that is uniquely you and yours. I know english/global rakuten sells patches, you can probably find loads (and at a better cost) in etsy and ebay/amazon. o.o You're right the bulk of your issues. You can make t-shirts , you're right though, the bulk of your issues will be with cardigans/jackets/sweaters which may be tough to find but if you sift through university online stores you can order them, I think some will ship online. o.o
Co&lu accessories can be found on taobao. If you want, I do know a couple of good taobao stores for co&lu items ?