I'm a complete newb, so any information is great. I'm based in Southern Nevada, and am so clueless on where to find material scrap. Mostly gonna lurk and read.
Nurdrage on YouTube has a number of videos on making nitric acid, as do NileRed, Doug's Lab and others. Nurdrage also has a good video on producing nitric acid from copper nitrate waste. Sreetips has a comprehensive library of refining videos.
"not shure on the purity... still waiting for glassware from china to go the diy way"
"Greenhouse grade" appears to be the same as technical grade, which is fine. Slight impurities and debris are ok. As long as the product is technical grade potassium nitrate or sodium nitrate, it should be fine. I'd avoid fertilizers which only list a NPK ratio, as you are technically producing a nitrating mix which could conceivably turn the wrong adulterants into high explosives. If there's no technical analysis or SDS available, you may want to chose a different product. If you don't want to hand over a copy of your driver's license, an alternative may be KNO3
stump remover. I've used Spectracide stump remover, and KNO3 from Duda Diesel, a bio-diesel supplier.
As you probably know, you can heat the excess water out of the sulfuric acid, so you can chose the cheapest source if you don't mind the extra step.
(As a note on safety, you should always handle sulfuric acid with the utmost caution. Hot sulfuric acid will permanently blind and disfigure you on contact. Using hot sulfuric acid is strongly discouraged on this forum. If you're educated enough on the dangers to proceed, then you will already know that you need to plan for every contingency and do it outdoors or in an isolated area [away from people and pets, with a concrete floor] prepped with all the requisite PPE-safety glasses/face shield, protective clothing- lab coat, long sleeves, eye wash, shower/hose, a fire extinguisher and a bucket of baking soda nearby, and someone who is aware of what you're doing and can help you within shouting distance. This obviously applies whether you're concentrating sulfuric acid, or making nitric acid) You don't want to boil the acid, you want to hold it at a high heat until the water is driven out, and the only suitable vessel is really a large borosilicate beaker or evaporating dish. In my experience, the Rooto is about 93%, which is fine for making concentrated HNO3. If you want red fuming acid, you'll need to drive out that extra water with heat, and dry your nitrate salt in a shallow dish in a low oven for an hour or so.
Seeing as for refining purposes you don't need such a high concentration, and you want to minimize labor and exposure to hazard, it's probably best to just start with the 93% and just distill your acid.
If it weren't for Chinese glassware, many of us would be priced out of the hobby. For the record, the only glass I've had break so far is my Kimax.