Hi I am a newbie and I am planning to invest ETH coin but I only have limited amount of money to start investing. Can I buy less than 1 ETH?Your response are greatly appreciated.Thank you. 
Yes, it is possible.Only requirement is that you have account in any exchange and funds in your BTC wallet to purchase ETH. There is no limit to buy 1 ETH, you can buy for any amount and you get ETH as per your buying value. No limit on minimum buy on any altcoin but some exchanges require minimum amount of buy. Bittrex require minimum buying of 0.00050000 BTC and Yobit require only 0.00010000.
Yes there is no limit, but you have to meet these exchanges primary criteria to buy your altcoins. My suggestion is to invest a minimum $50 because you will get a decent profit. If you invest less than this amount, then it is a bit difficult to increase your ETH with trading. Or else the same amount you can invest in less value altcoin and increase your bankroll after reaching once decent amount you can buy ETH, it's your choice.