Have you tried foam earbuds instead of the rubber ones? I found them less susceptible to slipping generally, especially when they get a bit sweaty. Maybe the cheapest thing to try next.
Failing that, another vote for bose soundsport, i find them very secure.
I've used JVC Marshmallows in the past. You can squeeze them like an earplug and they expand in your ear. Very much cheap and cheerful but that's what you're after right?
Have you tried foam earbuds instead of the rubber ones? I found them less susceptible to slipping generally, especially when they get a bit sweaty. Maybe the cheapest thing to try next.
Failing that, another vote for bose soundsport, i find them very secure.