Seems to me there is a guide or two or three or four out there. Pretty sure most of them involve converting.
I base my efforts upon things I would be ok getting stuck with 30 of if the Market drops out as that does happen periodically. You can never have enough Kismets, LoTGs or Glad Procs after all
Knowledge of what people want is of course useful. Honestly though, the stuff you want is what everyone else wants too.
Flipping is a valid lifestyle choice.....easy money to be had. Or Market Price Analyser and Correction Specialist if you prefer.
Another option is the Slotting an ATO, making it Superior, unslotting and selling for mad cash method. This requires a 50 of whatever type and you do run the risk that you will forget to slap in new enhancements for yourself to actually use.
It happens.....trust me.
If you have the influence for it, gambling on hero/villian/winter packs is another. Too rich for my blood but people seem to do pretty well with it.
Hmmm...think that's it but probably missing a few.
Lots of ways to make influence off the sweat of others. Takes a bit of work initially to figure out your prices, but once you do the patterns wil begin to emerge and you just sort of roll along earning as much as you want.