You can. It can take a bit of work and just know that to get the higher level materials and what not you'll have to do the story. Any time a new set of glamour gear or crafted raid gear comes out those tend to sell for a lot of gil. Along with food and potions people use while doing raids. Housing items can be a little hit and miss. Things like Aquariums, walls, floors, food that counts as furnishings and fish are also probably good money makers. Then there's all of the crafted minions and bardings for chocobo's. Try to have a geared fighting class so you can try and get the rare mats that drop from raids, primals and dungeon drops like manor varnish/wax.