Unipack / Create / Sports Direct singlespeed track bikes?

Ed i wouldnt call that a small effort, you make it sound too easy. I mean finding the frame etc. takes time.
A small effort would be to buy a Unipack (unfortunately)
With yours you'd need some bike assembly experience rather than none required to purchase a Unipack.

*Disclaimer*I am in no way on the Unipacks side.Disclaimer

I didn't pay for the frame, I pay for the whole bike, removed the wonky gears, shorten chain, a bit of twinkle and it ride like a dream.

It's that easy with a little effort.