im the type of person who loves to buy my costumes online since im pretty bad at making one myself (trust me.. its terrible) but then, if you ask about my opinion, its better for you to make it yourself if you know how to do it.. i dont recommend on buying your costume online (even though i bought most of it online) because it is far more expensive then buying it at the store.. you need to pay for the shirt, shipping, and delivering.. plus, you cannot try the costume.. sometimes, the costume dont fit you or worst case scenario, the costume you bought might not be delivered to you or the costume is totally different from what you'd order..

if you're not good on making one yourself (like me) try to find it in stores nearby or buy a dress and some similar material and ribbon and stitch it (if you want to do a lolita dress)

buying online would be the last option.. smile
well.. this is only from my experience though.. it might not be the same as other.. different ways from different people.. smile