Under 1" then the survival rate can be low after moving especially in the post. Most LFS here will not take them under that size, the bigger the better really.
I bought 4 from a chap 2 minutes drive from me at about that size and lost 3 of them. I would wait really till they are bigger especially if you are going to post.
They are way too small and unlikely to survive a transfer. It's not just about the length they need to have filled out a little too. they should be at least an inch to sell, preferably more. The bigger they are the more you can ask for them
the smallest ive parted with were just over 1 inch long ,my lfs wont take them under 1 inch but i hold on to them till i no theyve had a good start so mine are between 1.5 inches to 2.5 inches and very fat and feeding well on different veggies as well as algae tabs ...
ive sold and exchanged a good few hundreds without any probs .some lfs give about £1.00 each cash while some give £1.00 each as instore trade in..yet 1 store sells them at £7.99 each so the stores making a tidy profit ..but i trust the lfs better than p@h or other lfs so im happy with what i get ..as i no fish are looked after well ..
ive constantly got batches breeding ive tried removing caves etc but they just breed on a rock so ive always got some growing on ..ive found that in the tanks with greater aeration and more frequent water changes they grow much faster in fact ive had ones born weeks later that have surpassed older ones in size ..
if you can hold onto them longer they stand a better chance of survival and your more likely to make regular sales at your lfs if they dont have any losses..kaz x