If I have enough aphids, they’re kind of already enough of a lure. The plan of let them run wild until the ladybugs show up only really works if they’re on mature plants that won’t die in the meantime.

But also, I have better luck keeping them around for longer if I make sure to spritz some water all over the plants every morning/evening after release (until I find eggs on a leaf at least). If they’ve got food and easy to access water, like droplets on leaves, they tend to stick around.

You are right that they will just fly away, usually just after 1 day of hanging around.
But it’s really not good to purchase ladybugs anyway. They’re not raised in an insectary, they are taken from their native homes. Also, their immune systems are hyper-localized so when the purchased ladybugs inevitably fly away, they breed with the local populations and end up weakening the immune systems of the subsequent generations.

I’ve never tried a “ladybug lure” but you can attract them yourself by planting native, or at least localized, flowering plants.

You can however purchase green lacewing larva from insectaries or their distributors. The lacewing larva are known as “aphid lions” and they certainly live up to their name. A cheaper option, although a bit slower, is to purchase assassin bug eggs. They come on little paper cards that you hang on your plants and will hatch after a week or so.

If you can buy them as larva you might have a better chance of them sticking around. They don’t have wings but still love eating aphids and other little pests.