I dipped my toe in the marketeering pool yesterday afternoon. I spent several hours studying the wiki page for enhancement sets and researching prices on the AH until I felt comfortable buying six recipes. I had 8 converters on hand from drops, and a Babbage pop right before I planned to start converting netted me a quick 6 merits which I used to buy 18 more converters (although I had plenty on hand, I just like killing giant monsters).
I started with 4M inf and spent less than a million (not counting the value of the converters I used), much of which went to listing fees. I was conservative, and after the initial conversion by type to get a rare, I think I did at most two conversions by rarity per enhancement, using 19 converters total. In each case I ended up with enhancements that listed for a minimum of 2.5M. I figured for my first time out, that was a pretty good result, and I didn't want to throw too many converters away chasing something better. I didn't write down the enhancements I ended up listing, but as of this morning 3 had sold for a total of 11M, and the other 3 are still waiting to sell. I know that is chump change to the hardcore, but for someone who would not have even considered this a week ago, it was an encouraging success.
I'll add to this, and it will likely not be news to any veteran marketeers but for other newbies like me it may be helpful. There are a handful of recipes that appear as a rare within an otherwise uncommon set. For example, Dampened Spirits: Recharge shows up with the orange (rare) name, but does not use rare salvage and when converting, it is listed as uncommon. I thought I was being clever and buying a cheaply crafted rare recipe (and thus saving myself 2 converters), but that wasn't the case. I apparently wasn't the only one fooled, though, because the "Bidding/For Sale" ratio for that recipe was MUCH higher than the rest of the pieces in that set, although the recipe itself wasn't overly expensive (10k or less). There are similar instances in the Undermined Defenses, Mocking Beratement, and Kinetic Crash sets (which I know from personal testing), and I think Adjusted Targeting and Efficacy Adaptor also have recipes that fit this category, but those recipes were too expensive for me to try them.
One other oddity I noted was that my very first conversion by rarity netted me a Winter's Gift enhancement. I assumed this was a winter enhancement so it threw me that I landed on it, but it must be coded as a rare IO. It didn't have an impressive list price so I converted it again for something better.
Anyway, thanks again for such a great guide (and for others who have written marketeering guides). I quit live way before the invention system even came out so learning about IOs and sets and conversion has all been new, and working through this process has been a good way to help get up to speed on a big aspect of the game that I missed the first time around.