Yep, really good advice from both Satya and AGS. Direct approach to the brand owner in regards to accessing their authorised distribution channels is about the best way to go.
General rule, the bigger the brand name, the tighter the control and the less chance you will have of accessing it at supplier direct prices. One place you will not find genuine designer brand name clothing is in China, no matter what they say, no matter what the price!
Depending on the actual brand, liquidations can be a good avenue, however there are plenty of pitfalls when dealing in the surplus market as things are not always as they seem.
The biggest tip I could give anyone when dealing in surplus, is to ask question, after question, after question. Even what you may thing is obvious, get them to confirm it, and should they grow tired of your questions and start ignoring you, then you need to be looking for a better supplier straight off the bat.
Areas you should be looking at in the surplus market is loads of master cased goods, or A1 stock (new overstocks). Anything under those two type of loads and you are starting to look at loads containing customer returns, and from there you are starting to get into risky territory unless you are fully aware of what you are buying and what will be required to sell them.