If you're going to be a day trader, you really need to know your stuff. It's risky, to say the least.
One of the most important elements to being successful is having access to very fast data streams so that you can make moves quickly as trends stat to develop in the markets. If you're planning on doing this using consumer-grade sites like eTrade, that's not a good idea. The web systems of many of the retail brokerage firms are not good enough to give you data fast enough for you to make good, timely decisions or to be able to execute trades way that day traders do in order to make their money. Many of those guys are living on very thin margins, sometimes just a few cents of movement one way or the other, so they make up for it with a large volume of trades.
One of the reasons you were told you need a big chunk of money to day trade is that some firms will rent you out a "desk" and computer access to day trade through their systems if you're really serious about it. They will require you to put up at least a minimum amount of money for this privilege, and $25k may not be too far out of the ballpark.
If you've never done day trading before, be careful. It doesn't take much to get caught looking the wrong way on a trade that you can't get out of without losing your shirt unless you're willing to hold on to the stock, which could be longer than a day.
Day trading sounds very simple and easy, but it isn't. You need to learn about how it works (a good book to read to understand this market is "Flash Boys" by Michael Lewis, besides being very entertaining), because it is a space filled with very sophisticated, well-funded firms and individuals who spend huge sums of money to gain miniscule advantages in the markets.
Be careful, whatever you do. And don't play in day trading with your retirement money or any other money you can't afford to walk away from.
I hope this helps.