Dave:
First of all, welcome to the heroin den! From today forward, you life's mission will focus on how to get more STUFF, so you can make more STUFF.
In a feeble attempt to answer your question, I must first make personal preference disclosures. I HATE ANYTHING that uses a 7mm twist transmission.
For me, those component sets have been a never ending source of frustration. YES, you CAN buy a slim set (in quantity, for UNDER $1). BUT, if you make pens for HIRE, you must change out the WORTHLESS transmission for one that will actually last a year (Price +/- $1). Secondly, the ink in those sets usually run DRY between the 1st and 3rd show (Price for a quality refill $2-3)....NO disrespect for the $1 Private Reserve Cross type refills, as I've sold THOUSANDS of them and they are good. BUT.....(depending on the season of the year, is all I can figure...THEY MAY OR MAY NOT LABEL their refills). THIS IS A LOGISTICAL NIGHTMARE, for creating a system to help you know if you have changed the refill or not. The REAL Cross refills (labeled A.T. Cross- made in Lincoln, RI don't exist anymore). AND after MUCH recent research, I can't help but believe that the Private Reserve refills are EXACTLY the same as the Genuine Cross refills that are made in China.....Not a bad refill, BUT NOT INK that (in Ed Brown's words) will sell a pen.
Now, LET'S TALK PLATING. The $1 pen set looks pretty bad after the first user touches it. I'VE TRIED "upgrading" to Rhodium, TN gold and Black TI (which start at wholesale at about $3.50 -buying by the thousands). AND THOSE SETS USE THE SAME CRAP TRANSMISSIONS! The only longevity success I've had with slim plating is "upgrade chrome" and Black TI".
Since I warranty my work, I figure buying the "best of the best" slim hardware costs me about $7 -because it STILL comes with the Schittty refill. THEN, WHEN they fail (NOT, if they fail), I have at least $5.15 MORE in postage to return the reworked product to the customer.
The wholesale distributors (NOT the IAP vendors) will tell those who by slim sets by the thousands that the "PLATING PROCESS FOR SLIMLINES IS EXACTLY THE SAME AS WITH ALL OTHER SETS"....This is a convenient "head dodge". While the PROCESS is EXACTLY the same, the small "footprint" of the slim means that to have the strength to withstand the pressing process, the brass, lead, or WHATEVER METAL is under the plating must be thicker.....therefore the plating OVER those metals is MUCH, MUCH less.
SO, since the ink refills for slims SUCK (even the Fisher pressurized -the best I've found), the transmissions SUCK (even many of the "upgrades"), AND the "coating" (VERY FEW pens are actually "plated" anymore) SUCK, WHY NOT JUST SPEND $1-$4 more and buy a set that uses a Parker style refill?
The "stock" Parker type refill is NOT terrible and the "upgrade" inks for Parker style pens WILL SELL THE PEN for you!
"Coatings" (TN, Black TI, et al) are MUCH cheaper than metal, so the bigger pens are made with just enough metal to "make them strong enough" and MUCH MORE FINISH COATING MATERIAL.
After YEARS of selling "Sierra type" pens ( I DON'T sell the black enamel), I've have ONE plating failure. The only "transmission" failures I've had were my OWN fault for NOT including in a "how to change your refill" instruction sheet.
This is just me, but I'D MUCH RATHER put a product that I KNOW will write well, WITHOUT failure that putz around with sets that i feel like i'm "backing up into the sale" pens.
I don't even give away slimes, because I feel it tarnishes my craftmanship.
Respectfully submitted,