No! In fact, most customers do not purchase a whole ethereum, whose price exceeds $200/ethereum (as of July 2019). One of the benefits of digital currencies is you can buy very small fractions.
We aim to make it seamless for newcomers to try out ethereum so we have very low minimum purchase amounts. The smallest ethereum amount you can purchase is $1 from a EtherXATM. This is to ensure that after fees, you are getting a positive amount of ethereum.
The amount of ethereum you receive is based on the real-time exchange rate at the time you make your payment. The live EtherXATM exchange rate can always be seen on the EtherXATM home page, in the navigation bar, and on the order number generation page.