You'll definitely want to ask around, and a biggie for you is to probably go to a firm that will cover software fee's, or at least where they are managable. Many full time firms have software fee's around $200 - $300 per month. If your trading will cover this, then maybe it's not a big deal, but, you more than likely want a firm that allows this, and won't charge you software fees. The only firm I can think off the top of my head that does this is Cy Group Trading. Hear good things about them, I don't have any personal experience, but I do got a friend that trades there, and he has not had an issue. You will probably be at around .005 - .007 area, but it depends on your volume. So, just a few things to take into consideration if your doing it part time. Definitely ask the firm about this arrangement though to be safe.
I have to agree with Mav on this one. Our experience, when we let people "try" when undercaptialized, is not very good. There may be some firms that will let you come in with that amount, but I doubt any of the top firms will. This is hard enough when properly captialized. An option might be to find a successful trader/group who will put you under their wing and guarantee your account while they help you. All the best, Don