I purchased an upright trike a Schwinn Meridian that is sold at Walmart for $248.56 for my 85 y.o. Mom after she lost her license.
http://www.walmart.com/catalog/produ...uct_id=5679542
She found it to be "unstable" despite the overwhelming excellent reviews. I don't know if it was the "idea" that she had to ride a "granny" bike or the fact that the handling was simply foreign to her. She never rode the bicycle. I brought her to the bike shop for a two wheel bicycle but she had trouble with balance. We gave up the idea on two wheeled bikes after she tipped over a test bike in the parking lot much to the shop owners shock.
In retrospect, we should have tried one of the Sun tricycles like Tom Stormcrowe's wife. It appears much more stable.
The only bit of advice, I can give, is bring grandma to the shop. Let HER make the bike selection. If you try to get it for her, she may reject it.
