In fact, you can play most IF games for free, and many of those online. The IF community that I've recently become a part of has mostly been a hobbyist community for the past 20 years, with people releasing games and creation tools completely for free. One of the most well-known people in this community is Andrew Plotkin, aka Zarf, who has not only made some awesome games but who has contributed a lot to the community in terms of various infrastructure for making and playing IF games. Well, Zarf has decided that he'd like to take a stab at working on IF games and tools full time, so he started a Kickstarter campaign for an iPhone IF game. He met his modest goal of $8000 almost immediately, so he is going to quit his job in a few weeks and start at the beginning of the year as a full-time IF author. He's currently got more than $27,000 pledged, and there is still an opportunity to give more until Monday, December 6. Why give more? Well, for one thing, you get rewards for donating. For $3, you'll get a copy of the game when it comes out (which will cost $5). For $25 you'll get a copy that you can play on your PC/Mac/Linux machine (basically any machine that can run an IF interpreter). And there are other cool rewards for higher levels. Also, the more money he gets, the longer he can continue to give this experiment a try. You can check out the games he's already made, and there's a teaser for his new game up, too.
And finally, if anyone is interested in IF but isn't sure how to get started, I'd be happy to get together in person and play some games (I did it for my father-in-law over the weekend).