Inflated opinion
Fed up with scrambling round filling stations trying to find and often having to pay to check and perhaps inflate the car tyres, the Mrs has suggested we buy one of those 12v air pumps instead.
Never used one and no idea if they are any good or of any value, so has anybody got an opinion on 'em as I'd hate to waste twenty or thirty quid or whatever on something that might be totally useless.
Two types 'out there' - mains and/or 12v plug in.
Once upon a time... I had a Renault 12.. which had inner tubes in the tyres... often had punctures.. and kept a puncture repair kit plus the tyre levers in the boot.. along with an already repaired spare tube... having to use a foot pump once... trying to get the bead to reseat, was a nightmare... so I bought a 12volt plug in tyre inflator from halfords for about £6 and it worked fine... actually it was also used to pump up a tourist coach front tyre which had stopped outside my motor accessory shop in Preston a few years later... and they is really big tyres !..
so now I always carry my trusty tyre pump... and it is excellent to check the tyres at home once a month or so. ( also got a couple of different pressure guages, for a quick check) . Remember... under or over inflated tyre pressures. and uneven tyre pressures can cost you money... firstly in tyre wear.. secondly in MPG. and thirdly, if you have an accident, and the tyre pressures were wrong, the insurance company can void the policy, saying that you neglected to make sure the car was properly maintained and roadworthy...
so.. YEP definitely.. keep one in the boot.. and use it often.. (also saves you having to pay for "free" air as it used to be ! ! )
This is a "modern" updated version of the one I bought.... same thing, different casing ( more modernish) .. !
https://www.amazon.co.uk/260psi-Compressor-Built-Flashing-Hazard/dp/B001HCSDR2
I've never owned or used one of those (so I've no recommendations of any particular device), but I've heard friends mention them.
You can get combined tyre inflator / jump starters which means only carrying/stowing one item such as this one (which when I clicked on it offered "40% off your first purchase" via a pop-up coupon code).
About 3 months ago a friend who'd just had his alloy wheels refurbished was having problems using his portable inflator to check his tyre pressures due to the very short length of valve stem left exposed (slightly more than needed to put a dustcap on) for neatness by the refurbishing company, and his attempts had led to him releasing air.
I've got an airline PCL (garage type) inflator which is connected to a compressor so I told him to bring his vehicle round to my place to try that, but that still wasn't successful until I screwed a valve extender (like a sort of dust cap with an opening on the end of it) borrowed from another car.
I started inflating his tyres and he told me "No need to do that one as I've checked it and it's correct." but I did it anyway.
He wanted 29PSI 39PSI in all wheels tyres and the one which he'd said was OK was only registering 35PSI on the certified accurately calibrated PCL inflator (which is less than a year old).
The moral of that little tale being that although they may be handy for inflation, don't rely on the accuracy of the pressure gauge, and maybe use a secondary tester such as this to verify. 
I haven't visited Halfords for quite a while but I had some time to kill a couple of days ago whilst waiting for my car to be MOT'd at another nearby business so spent about 15 minutes wandering around in there. I was shocked at some of the extortionate prices being asked for things such as windscreen wiper blades etc. compared to online prices for the same brands of items from different companies. 