I did mention "non production" and the guy who does a "few things here and there" like I imagine most do here. I'm not sure what a decent volume order is for you but am sure it encompasses more than a "few things here and there" which is why I specifically mentioned non-production. Example guy sells 20 licence plates for $20 each or $400. For ease of math plates cost $5, paper costs $1, everything else but ink is free. For ink we will use sawgrass estimates of .60 (ease of math) for 80sq" @50% (Lic plate is 72sq" + a border for bleed - close enough to 80sq"). So a sawgrass plate would cost $6.60 20 would cost $132. A non sawgrass plate would cost $6.12 (20% of sawgrass ink cost) or $122.40 a diff. of $9.6. So the gross profit on a sawgrass plate is $268 non sawgrass $277.40 NOT a big deal. Now if I were doing 6000 of these a year it becomes important, but I would bet my bottom dollar most people here using sub systems don't do $1000 per year in all they do using desktop printers. I run 2 as you know (you helped me with one) and prob do about 5K in sub work a year - no where near production or approaching it so just using that estimateof $400 in sales which is approx 12 times the example or $4,800 (close enough to $5K) 12 x $10 difference is $120 over the course of $5K in sales - Not a big deal to me but it could be added to the bottom line which is why I said as a smart accountant I should use the cheaper one but don't because the other is faster. How much $'s does speed count for? Additionally, with my program, I didn't have that large of a discrepancy .57 vs .12 mine was roughly half which would reduce the savings to only $60 over the course of $5K in sales - even less of a big deal for me.
If you run large order runs for large graphics like you talk about 13x19 - I would consider those production runs and not fall under the category of doing a few things here and there. It is of my opinion that most here don't operate in a production mode, including myself. If or when I get to that point, Larger volumes of paper, substrates, and ink will all become cheaper due to volume purchasing and would gravitate in that direction but for most I think the difference of roughly $10 on a $400 order doesn't amount to a hill of beans for us low volume people. It certainly shouldn't be enough to scare anyone off about the price of ink and prevent a start-up.
that's my story and I'm sticking to it.
PS I'm not sure what the coverage was as I lost the program when my pc crashed last sept. The only thing i have is license plate .57 vs .32 for ink costs for the 2 printers so that's what I am going by.
I'm home based and dye sub on the side. Most of my items are large enough where ink costs matters. My ink cost savings are around $200 a month give or take. I prefer to put that in my pocket.
$1000 per year in sales is not my idea of success, why even bother making $20 a week.

Many come and go in this business, most fail to make back even their initial startup costs as the printer will fail printing so infrequently. If you look at the Ricoh graveyard posts here those became doorstops mainly due to the users not using them enough to keep the ink from expiring in 6 months and killing the printer beyond recovery.
Most successful desktop dyesubbers are either using dye sub in an existing
established imprinting related business as adjunct sales, typically this isn't home based. Or they are home based and pretty hard to make money just on very small items only, your ink cost matters if a significant amount of your items are 6 x 8 or larger and you are doing any decent amount of business.
The small trinket stuff alone you cannot do these home based in most cases and make it. I do know a couple of home based people that only do mugs, but they specialize in those and offer them wholesale in volume.
I do some mugs but most of my stuff is tiles, t-shirts, mousepads, murals, and chromalux panels. A few totes here and there.
I suspect you are basing your perceptions of others business models based on your own, but without an existing sales base of other imprinting products then those looking at starting a business from scratch starting out with dye sub will likely fail to make it unless they are doing tshirts and some other larger photo novelty products where the demand is. Many photo novelty items the ink coverage is more like 75 - 80%.
If you get an entry level SG system like the smaller Ricoh, heat press, and a few items and accessories you are at a $1000 investment and if you only print a $20 item once a week your printer is dead before you get a chance to make your money back.
You can't really make much of a t-shirt business home based with the smaller printers so you are looking at $2000-$2500 for a larger Ricoh and a 16 x 20 heat press. Then even with that you are taking $2 per shirt out of your pocket and giving to Sawgrass.
While you mention "non-production" volumes then unless you are only needing adjunct sales for an existing business then your thinking is wrong, if you are home based and wanting to make any decent amount of money you need to
quickly get from doing a "few items here and there" to production volumes as part of your business plan. Otherwise be like so many that start out here from scratch and fail and the only winner is Sawgrass and Ricoh or Sawgrass and Epson.