I wrote gdebi a long time ago to make it really easy to install .deb package with proper dependency resolution from the commandline and via a gtk (and kde) UI. But another neat (but not very well known) feature of the gdebi-core cli tool is to install the build-dependencies of a debian source package. If you run:
$ gdebi debian/control
in a unpacked debian source package it will check for missing build-dependencies and offer to install them.