If you are building a blinky (processor, LEDs, supporting components) running your project directly from a few AA batteries is a great choice. In my testing, despite violating the electrical specifications, the ATtiny85?V? has been reliable down to 1.6 volts (at which point the batteries fail). The ATtiny85 (no-V) should have no problem running directly from 3 AA alkaline batteries; even at 8 MHz.