Standard in the MIT inventory is the Roland CAMM-1 GX-24 wide vinyl cutter, it cuts 60 cms wide. Price around € 2000
If 30 cms wide is sufficient, then the SILHOUETTE CAMEO is great for only € 300.
The Cameo2 has USB and an SD card, when you replace the knife blade by a pen, it doubles as a plotter .
The new Cameo3 has a double carriage, so blade plus pen, and bluetooth.
The Silhouette Studio software is extremely friendly and intuitive It is free, not open source and will import .dxf files from any 2D package. Mac + Windows. A $ 50 software upgrade will also directly import .svg files, saving you the conversion from svg to dxf in inkscape. It is a fun thing to take to schools, as it also can print stand alone from an SD-card. Cameo3 from USB.
Silhouette also has a smaller cutter, the PORTRAIT, which is a revamped version of their previous SILHOUETTE SD.
It accepts 20 cm wide, A4, and uses the same software: $ 180
An overview of 11 small cutter/plotters can be be found here.
A note of software: most cutters can be addressed open source via Ubuntu – Inkscape – InkCut extension.