A friend who is a school nurse insists that the best blood pressure monitor is the old fashioned kind... With the velcro cuff and the little bulb thing that you pump by hand.
I once tried an electronic version and the results were so wildly inconsistent that we declared it unreliable and it went right back for a refund....
CVS has one on sale today (I don't know how long the sale is in effect, or if that is the regular price)...
So I picked up Blood Pressure Monitor: Self Taking for $16.99.
Model #BPAG1-20CVS
CVS Item # 800232
They are behind the pharmacist's counter...
I recommend you get one to keep around the house... For yourself or a dizzy friend, relative or neighbor...