Blood pressure meter - which one?

CiniO

I have two blood pressure monitors at home.
One is the wrist battery operated - Omron. Something like that:


Other one is Sanitas also battery operated, but upper-arm. Like that:



The problem is, that they show different results.
While one shows pressure of f.e. 115/75 (the bottom one) the first one will show about 135/90.

Now I don't know if I can trust any of them.
I thought if I get something like here: http://www.ebay.ie/itm/Sphygmomanometer-Blood-Pressure-Meter-Stethoscope-UK-/330279266402?pt=UK_BOI_Medical_Lab_Equipment_Medical_Equipment_Instruments_ET&hash=item4ce62da862

Will this be the most accurate meter I can get?

Nonoperational

The upper arm machines are the ones to go for. You would pick up a clinically validated Omron machine for around €50-60 (eg http://www.amazon.co.uk/Omron-Comfort-Upper-Pressure-Monitor/dp/B004XCWY1Y/ref=sr_1_13?ie=UTF8&qid=1329612181&sr=8-13). Not sure if that Sanitas one is clinically validated but if it is, and it's upper arm then it's going to be pretty accurate provided the cuff isn't too big/small.

Make sure it's clinically validated and always take 2-3 readings twice a day before you jump to any conclusions about blood pressure.

You can get a sphyg and a steth and try, but it's pretty hard and annoying to take your own BP that way and it would be no more accurate than a good machine.