I think for a while I really struggled to find pastel Goth pieces that were not ridiculously expensive or unavailable outside of Japan. But I think a few places have popped up that are affordable and have really good pieces.
Firstly, Sheinside, which I believe is based in china..
Next is Romwe, which is pretty similar to Sheinside
The shipping is also free and it carries quite similar products to Sheinside, I am tempted to try it out at a later date, but I have read some reviews and the customer service seems to be good
http://www.romwe.com/
Miss Rebel is another example, it is UK based, and carries a range of clothing for pretty cheap prices, I have ordered from them a few times and within the UK the shipping takes about a week. Not all clothes are Pastel goth or even Japanese fashion based but if you look carefully there are some gems
http://www.missrebel.co.uk/product-Holy-Mary-Print-Sweatshirt-20902
http://www.missrebel.co.uk/product-Ying-Yang-Print-Knitted-Jumper-21013
http://www.missrebel.co.uk/product-Skull-N-Bones-Knitted-Jumper---Black-20833
http://www.missrebel.co.uk/product-Lace-Trim-Contrast-Panel-Bodycon-Dress-20431
http://www.missrebel.co.uk/product-Rabbit-Face-Knitted-Jumper---Grey-20844
http://www.missrebel.co.uk/product-Black-Zip-Up-Front-Pleat-Dress-20701
Also ebay and etsy can be your best friends, as long as you know what to search, trying being specific, ebay.com hold a lot of japanese and korean fashion, and etsy does a lot of cute and creepy accessories.
I hope this helped you guys, look forward to more posts soon xxxx