I've purchased a "cheap" USBasp programmer from AliExpress. It didn't cost much, however I'm surprised that it seems to work very poorly. In fact I can't get avrdude to receive a sane response from an ATtiny84 through it.
Rather than copy/paste everything I've written so far, I've written up the problem on Stack Exchange here.
The short of it is that although the Clock and Reset signals do what I expect, MISO and MOSI look very strange indeed. I've posted oscilloscope traces on that thread.
Is the programmer simply broken or have I got something wrong? I'm 99% sure my connections between the programmer and ATtiny84 are correct, but there's a chance I may have messed up somewhere.
I've spent three evenings on this now so I'd really appreciate some help from an experienced AVR freak, please! :)