Is it possible to get ticker of bitcoin.de using an api?
You could just parse the website. For example to get the current euro and us dollar prices:

curl -s https://www.bitcoin.de/de | sed -n '/EUR/s%.*[^0-9]\([0-9]\+\)\(,\)\([0-9]\+\).*%\1.\3%p'

curl -s https://www.bitcoin.de/de | sed -n '/USD/s%.*[^0-9]\([0-9]\+\)\(,\)\([0-9]\+\).*%\1.\3%p'