Power saving mode with Arduino and several modules

Hello, I'm designing a project where Arduino Uno is connected to an SD card module, an RTC, a temperature and humidity sensor DHT22. All battery-powered. The data log is made every 10 minutes. I need an power saving system. I have a ATtiny85, I have programmed in Watchdog Sleep mode. My question is this: how can I cut the power to the modules (included Arduino) using the Attiny? I'd like a step-up regulator with enable pin, I have seen of pololu but is expensive for me. Does anybody know any? I also could use a MOSFET? I need a scheme. Thank you. As a last resort, I will use a mechanical mini-relay ;-)