Vintage / Antique / Edison Style Light Bulb
All shapes and sizes, bayonet and screw type fitting.
I got a 60w one, most wattage varies.
Compatible with dimmer switches.
Found in Cardiff Poundland, with its own shelving so might be nationwide.
For a pound your room could look like a edgy, independent cafe or microbrewery bar. If you wait long enough, tatted up bearded hipsters could start knocking on your door. X)