Looking at getting one, there are some budget (£120'ish) 'industrial' self contained units albeit with bulky 17mm camera heads but also dirt cheap units for a few quid that plug into your mobile phone with 8mm camera head - are they any good? What sort of focal length would be best 5-15cm? Have a problem with suspect rodent activity and suspect some wiring damage in engine bay (non zed) and want a general look around for damage initially (hence up to 15cm focal length probably best) with the ability to focus closer if necessary. Anyone experience with them?