to the person who didn't want to spend more than 50 quid:
http://ukvapers.org/Thread-For-Sale-Sigelie-Zmax-V3-Telescope-Efest-IMR-batteries
Either a Vamo or SVD (I prefer my SVD now) would be a good budget upgrade. Better battery life than the Apollos, better fine tuning of voltage, variable wattage. And the option to go either 18350 mini mode or 18650 lightsaber mode. Only £25 from fasttech too (plus batts)
Thanks both - exactly the sort of suggestions that I was hoping for. I'll go and do some research on both (am on UKvapers as well), so I'll do a bit of searching. Either looks like exactly my sort of thing. Just worried about too much rattle etc as I know the VAMO was a bit inconsistant depending on the batteries etc.