Ok I shall start the list - high quality only right?
Most of mine will be large or Australian companies
Leg Avenue (be careful alot of their models are wearing things that do not come in the costume kit)
Dream Girl ( I like them cause they make almost everything in a + size to)
Foreplay
Fantasy Lingerie
I would advise staying away from adult shop, Club X and the big chain places you find - they just buy from those first 3 companies anyways from what I have seen well when it comes to costumes they do
If you're looking for something more gothic like or in leather you could try places like
Elegant Leather
Most of the stores should have some type of catalogue for you to look at if you want to as well ( as in actual in person adult stores)
My only really useful piece of advise for you is to check what it will cost for you to purchase directly from the company and how much it would cost to buy the same thing through a retailer - the two can be VERY different.
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Close to impossible for me to dress up for the SO really when he looks at me in anything linegrie / sexy like and I know about 6-% of his brain is going " It would have been better if she had worn something in X cut and Y colour"
One of the few disadvantages to working in the adult industry