You will have to be quiet lucky for finding things on eBay or etsy. EGL community is a great starting place to start finding out about brands and where to buy.
Both
hellolace.net and lolibrary are very good databases to find things (I am partial to lolibrary, but hellolace has good reseources).
There are also several secondhand places where you can buy brands, such as the egl_comm_sales LJ community, closetchild (
closetchild.ocnk.net), Fururun, Tokyo Alice.
Always research before you buy.