Hey there,
I don't know much about goldsmithing, (i'm only level one and got there with Yag Necklaces + Lightning crystals) - but a good friend (RL) of mine happened to hit level 17 yesterday. He told me that he spent about 100k to get there. He's only been levelling GS for a couple days. What he did, and has also proven to offset some of the costs and make it a little cheaper to level, is that he went mining. He hadn't done it before, but decided to try it. He bought some field gear and went at it in Gusgen. He's had quite a bit of success with it and has mined a total of about 20 Darksteel Ores, a few Gold Ores and some other stuff that he's used toward his Goldsmithing. He is level 61 BLM, so he can run through Gusgen with no aggro and with your level 43 Bard, i don't know that you can do that.
I really don't think this will be much help to you, but I try to help out wherever I can. My advice being that for such an expensive craft to level as GS (the most expensive from what i hear) it might be in your best interest to level up your main job enough that you won't get aggro in Gusgen, and then go mine to offset some of your material costs. My friend doesn't spend too much time mining, and I'm rather surprised at how successful he's been.
From what i've seen on the AH, darksteel and gold ores go for about 12-13k a piece, which at least makes it seem like it's worthwhile to mine.
AGAIN, I'm not an expert on this, nor do i even claim to be. I mainly posted this because of the coincidence of both you and my friend being the exact same level, but the discrepancy of gil spent to that level (300k Vs. 100k)
Although i understand you're probably very eager to level your GS up, it just doesn't seem the most realistic craft to level without being able to efficiently mine.
I chose to go the route of Clothcrafting to start and it was VERY expensive to level without going out here and there and farming some materials. In the process of farming, I decided to essentially kill 2 birds with one stone. My leathercrafting was at 0 - and my cloth was at about 30 at the time, so i went over to Konschtat and trained loads of sheep. (i brought some stacks fo wind crystals along with me and I would take the sheepskins i got and synth them into Sheep Wool - which levelled up my leather (cap 4) - i then took the Wool that I made and used lightning crystals (which i also brought) and synthed that into Wool Thread. After making some wool threads - i would then synth them into Wool Cloth (sells for 55k a stack). Throughout all of this, i levelled my leather to 4 - and each time i was synthing the Wool Thread and Wool Cloth....it levelled up my cloth.
The point of this little story is to try to figure out little tricks that can help you offset the cost of your crafting. Noone told me to do this, i just thought about it, tried it and it makes sense. Not to mention that I also justify my farming there by hoping that Stray Mary will pop and drop the Mary's Horn. Which would be a bonus. I wouldn't be able to do this, however, if I wasn't the level I am at. As a 61WHM, i can train every sheep there is in the zone, and while i'm running around collecting the sheep for my train, they chip away at me (1-4 damage per hit), raising my TP up...and by the time i've got about 30 sheep or more in my train, i'm at 300% TP, i just have to turn around and use Earth Crusher (AoE staff WS) and i kill everything in one shot. Then I watch as my inventory fills up with sheepskins, sheep meat, etc. Thinking ahead, though...i throw gobs and bees into my trains, for the Beehive Chips and the Animal glue, so that I can save myself some cash when i level Alchemy and whatnot.
Holy SHlT - i can't believe how much i just wrote. I hope this can be of some help to you in your endeavours and i honestly wish you the best of luck no matter what you decide to do.
P.S - don't work directly off-guides as what works on one server, may be crazy expensive on another. It's a little bit of trial and error, but when you find what works....you're laughing!