I finaly broke down and started skilling up a JC. I have wanted one for a long time but never got started. There are a few cheap things that can be DE'd that had my eye for a long time.
First thing I did was go mine some copper ore. I have a lot of gold, but there was no way I was going to pay 6G a stack for copper ore. This was the only ore that I gathered. I got the rest from the AH for fairly cheap. I took my time looking at the cheapest way to get some thing.
I have a minner, so when it called for bars of something, I was able to look at the price of ore instead. That saved me a good deal in some places. Having the option was the big thing. Some places I picked up half ore and half bars. Whatever was cheapest.
Prospecting ore is key to doing it cheap. There were several things needed by JC that was in limited supply (or over priced) listed in the AH where the ore was cheap enough to prospect to get those items. The one big mistake I made was prospecting fel iron ore for gems to cut. That was fine, but just after that I had to prospect several stacks of adamantite ore for the powder and got a better gem drop rate. I was done with those gems at that point so that turned out to be some expensive powder.
I sent off all the gear to be DE'd to get a little return on my investment. I am now 400 JC and can prospect saronite ore. I need to do the math again, but it looks like the price of saronite is getting so low that I may be able to turn a profit by prospecting it and vendering/DE everything.
It looks like I may be getting into the prospecting business.