I don't know your server's economy, so cannot really speak to that.

What I can speak to, though, is the matter of options. At 70 you have a lot more options as to what to gather than you do at 60, or at 50, or lower. I do not know what level you are, and my view of gathering is based on my own experiences, but I'd suggest using Collectibles and Leves to get higher in level to open up more options for your gathering. There may be something more valuable, or that sells faster, that you are currently unable to get due to your level, and until you are at a level sufficient to get it, you would not be able to capitalize upon it.

The drawback though, is the matter of gear. That can get expensive, either in terms of spending gil upon it, or in spending the additional time to gather collectibles for the scrip with which to buy it (time spent doing that is time not spent gathering something to sell).