That depends on your settings partly. How fast are your current buy times? It also depends on how full with people the shop will be, magic and stamp have a very high volume of people trying to buy so you'll miss more items. The more high profit items a shop stocks, the more full with people it'll be.
Sorry for my late response,
I've been ABing in Stamp and Magic, and I miss 100% of my RS in stamp it misses everytime and rarely buys.
My question is, do you have an idea for a safe delay settings for buying in stamps?
i've tried other shops but stamps are the only profittable ones that could really sell, other shopps doesn't sell much even on magic.
also, what's the most efficient ms delay in bbuying/ i usually gett 800ms-1500 ms sometimes more.