If you fancy a go yourself -
http://fnbcreations.net/Articles/FIREFLICKER.pdf
I am currently gathering the supplies as I want a welding torch effect, depending when you want to try (if you want to try) I will have some parts as I'm buying small batches of chips rather than single items.
A note to the link I saved for myself- if you have a DC source of 5V, the items left of the resistors arn't needed as that is a 5V voltage regulator and capacitor.
I am no expert, in fact I will be posting some questions of my own later as the range of chips is quite baffling if you don't understand the nomenclature. ???
Alternatively, I did find a pre-made fire flicker circuit for dolls-houses, however £17+ was a bit steep for something I can try for myself for under £2.