One solution is to temporarily enable swap on your micro instance. As described at this SO post, enable 1gb swap via:
sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
sudo /sbin/mkswap /var/swap.1
sudo /sbin/swapon /var/swap.1
Once swap is on, install scipy via pip:
sudo apt-get install -y libatlas-base-dev gfortran python-dev build-essential g++
sudo pip install numpy
sudo pip install scipy
Once scipy successfully installs, you can disable it via:
sudo swapoff /var/swap.1
sudo rm /var/swap.1