You can buy thru their slack channel. https://slack.iota.org
Buying there is a bit stressful because it's quite complicated because they are using trading bot. So when depositing an amount, make sure you have not missed anything because youll lose your funds if its not the exact amount you entered. Anyway, you need an invite in able to enter their slack channel. It's on you to find out how. If still you can't find out how. Then try these markets https://coinmarketcap.com/currencies/iota/#markets
Iota is now 5th at the coin marketcap. I think it will surpass XRP market cap and make it to the 4th before this year ends.