I bought this supplementary pile of parts, to see how good it is as a stand-alone set (I've already got lots of other components from years past). I think it's worth recommending, even if the lack of documentation in some cases means there's an element of mystery regarding some of the items (eg, stepper motor). Took an absolute age to arrive from China, but when it did, it was extremely well packed. Or at least, extremely compactly and tightly packed.
It's on ebay listed as “ Arduino DIY Starter Kit lcd Relay Stepper Infrared 1602”, an example right now is Item number: 120639924127.