No, end product from crafting dont sell well , as of now , only partial material for crafting sells well ( all rushing for higher level for crafting )

EG : weapons/armors lv1~25 some sells less than 300gil , but one of the material itself cost more than 300gil alone. . . . .

Mining or bonatic , in botanic got skill to boost shard x3 for each attemp , not sure about minnig.
Oh ya , mining/blacksmith beginning quest should also give out free fire shard in bulk , few hundred if not mistaken.

Actually if one want to skip that "hard" range of crafting is quite possible with leves , just do the lower lv courier type with HQ , it is actually much better than x3 submitting as it cost less gil & crafting time.

lv15 onward you need obtain the material from players/monsters , either mining/botanic/monster or buy the mats from market board as some component are created by other class, EG : fish glue by alcemist

Use gil to earn gil , buy mats, craft HQ equip and sell it in market board.
But this hardly earn you any if you consider the conpetency with other crafter that want to clear stock.
The solid way is via gathering, definately earn, eg : Flax , 70gil each.

Get shards as it is solid 40gil each min if it able to help you level up.
Eventually you still need to study your own server market to see which item serve you well with highest price.