I have been working with brands who offer drop shipping for almost eight years and I have never paid a fee for an account.
The companies that charge these fees are often middlemen suppliers who add a monthly fee as a way to make extra money. You should go direct to the brands they carry. That's what I do and there is never any upfront cost to do business with them.
I've never been involved with any fashion or clothing niches. The reason is that these items are prone to very high returns rates and I try to set up businesses that are less customer service intensive. I would think that the high return rates would also lead to many companies (brands) not offering drop shipping or maybe offering it with a strict no return policy and/or high restocking fees.
If you still want to proceed with this niche my advice would be to find other online only retailers (your future competitors) and extract the suppliers (brands) from their website(s) and then contact them directly for accounts. Just an FYI - these companies won't advertise themselves as drop ship suppliers, and that's a good thing ;)