Ugh... $1 would cost at about 50 in here... it's too much. What I can advise you guys to do anyway is to booty grab and hoard. Simple as that. I think that buying gaia cash would get me out of money so I guess I would skip that. And if you sell for a reasonable price in the MP, it would take quite long to sell. Plus are you sure that anyone would buy it?
Also, selling expensive stuff in the MP would be a bad idea. Since it takes out 2% of your fee, it would really be bad to do so. Especially for example, stuff that sells for 1M, if they take away 2%, it's taking away 20K, which can get you an item or two.
And as you said, selling in big bulks can get you rich. Yes, it can, but if the item doesn't inflate. You must make sure that it has a good stat. What you mean by selling big bulks is already hoarding which is done by buying a lot then re-selling them in the future.
Hoarding would mean, for example, in the year 2005, I buy 1000 kitty slippers for 20k each. This would cost 20M gold. Then in the year 2010, the value of the kitty slippers went up to 100k each. Feeling happy for the value, I decided to sell the bulk of 1000. So after selling them all, I earned 100M. That would be a profit of 80M.
Before I do hoarding though, first you must familiarize with the MP prices, LMP, HMP, AI's, etc. You must know when items would be re-released or not. RIG items are good or not? You must find out. Also check if the price increases and does not inflate. If your happy with the price, hoard it.
But to get the gold for hoarding I suggest you first booty grab, post in forums, and zOMG. Open daily chances, no it's not few, zOMG has like 8 of them. ^^;;
I hope this helped... >w<