If you search "5V Stepper Motor 28BYJ-48 With Drive Test Module Board ULN2003" on ebay it will throw up a host of suppliers (I paid £0.99 for mine).
Just check that the driver board is also included.
The speed is as seen in the video second two videos (it is real time) .. If you start pushing up the speed then steps will be missed, however i guess if you are willing to drive them with a higher voltage (mine are 5V) then speed would improve (however at the risk of burning them out ... (the driver board allows splitting of the data and motor supplies).
(With 5Volts the current is circa 200mA under load/drive and 220mA in stall condition).
Regards Gareth