hello, how much fg is worth of max gold stash?

15m in game gold sells for 30-40 fg so a full shared stash of 7.5 should sell for half that

I have a gold find barb on non ladder. and I do not intend to go into this ladder. is it worth farming on non ladder? do you think its a valid goal?

i think most will be playing ladder. if you use the search feature in the trading section there are more people selling gold then actually buying it so unless you underbid all of them i dont think you will have alot of success. fg could be made but it may take longer to actually sell then to farm the gold.