At 15-20g most babies are nicely established and shouldn't have any issues going to new homes. Under 10g I won't ship my babies because they are too delicate and if someone asked I would wait to ship until they were in the 15-20g range before sending them to someone inexperienced. They're very hardy little guys tho and over 15g they should do fine anywhere
I generally sell at around 15 grams minimum. I will sell even an 8-10 gram hatchling at a reptile show or from my home if I feel it's eating really well and growing steadily. I wouldn't ship any gecko under 15 grams.