...there is quite a difference in price between a makita with no battery and charger and one with battery and charger
Yes. Batteries for cordless tools aren"t cheap
Reading this thread I wonder how I've managed to make a living over the last 15 years using crappy, sometimes Chinese-made, "scammy" Makita tools I have. I must be a fool to have shelled out over £2k on this unreliable rubbish....
The fact is that my Makita cordless stuff comes from.the UK, Japan, USA and China. With the exception of the two tool outfit bought at the beginning (which came with two batteries and a charger) allmy tools were bought bare, i.e. without a battery. For trade quality tools that is pretty much the norm. I am on my 4th Makita 18 volt cordless drill (i have worn two out - I am a tradesman) and to date I haven't had a wobbly chuck.
My advice is that if you insist on buying the cheapest tool there is you are potentially asking for trouble - so only buy it from a firm with a bricks and mortar presence
in the UK. Otherwise an guarantee you are offered is probably only going be of use in the toilet. Don't expect a cheap tool to last, nor for there to be any spares available for it (although, surprisingly, spares can be had for many Parkside and Work Zone tools from a third party).
As to battery size for driving screws, my first cordless was a 7.2 volt Skil model which was used to build a load of studwork in a previous house. It was painfully slowand had limited bsttery life, but it worked, and it convinced me to buy a Bosch 9.6 volt set-up for my workshop (this was in the days when 12 volts was regarded as a trade tool and 14.4 volts had just made an appearance). So FFS stop flapping about like a dying fish, set yourself a (realistic) budget and see what you can get for it
And remember the old saw - buy cheap, buy twice