EBAY Newbie: Why are there listing fees?

[melissaA]

I just started selling on ebay like 2 months ago and have sold some things and all was going well. And listing items was free!

In the first month, I was only able to sell 10 items because I was new. So it got to a point where I wasn't able to list anything over the 10 items...

But then, this month, I was able to list a whole lot more (still for free). Today (I have about 40 items listed), suddenly, for listing an item, they are asking me for $0.30. Can someone please help me figure out why this is?

Did they change regulation? Or am I exeeding my listing limit?
HELP!
In response to schweppesy: Off of selling fees! Which aren't that little!! It'd be way more than enough... This is a rip-off! But, since it's a trial offer, how long did it last and why did it start all of a sudden?