I've got three right now and none ripe, but last time I bought some they never felt ripe and when I cut into them they were all brown inside. I lost all of them. I will try the trick with the stem end, I'd never heard that, but I'm willing to try anything!! We have folks on the side of the road that sell avacadoes, but I've never bought any...I rarely carry cash, preferring to use my debit card so I'm never ready for the roadside stands.
I don't know that I'd fare any better with them than the market though.