
NEMO
Disco 15 Series
Spacious for side sleepers; bulky, temp rating optimistic.

Running these analyses costs money. Buy through my links to help keep lights on! I may get a small commission.
No summary available.
I love my Kelty Cosmic Synthetic 20F
All of these suggestions are really junky except maybe the mat though. It's not like you couldn't go backpacking with them, but you could go much lighter without paying that much more. Borah bug bivy + 7x9 tarp: $184, ~15oz 3FUL Qidian Pro pack: $92, ~31oz CCF pad, whatever is cheapest around R2: ~$30 Ice flame quilt: $100-200 depending on rating You'll be out the door around $400-500 for the big 3, with a weight that should be well under 5 lbs, and nothing that you'll end up with zero use for later once you upgrade a bit.
Yeah I agree with you on the tent, it's a lot more comfy for most beginners. The 1/8" ground sheet is a solid idea too, though I do also think the eggcrate CCF pads are also great in combination with an inflatable, since they provide a more comprehensive backup in the case of inflation failure, and they also function as a sit/kneeling pad. Tons of ways you could go as a beginner. The right idea is to buy stuff which won't immediately become obsolete once you decide to throw a bit more money at the hobby.
I agree that these are reasonable suggestions, and that a Kelty sleeping bag, let alone an Ozark trail tent, is not. Though for a novice (who hasn't expressed interest in UL) I would probably guide them to an actual tent, like something in the lanshan series. Or a SMD gatewood Cape if she/he may go in the ultralight direction I'd also suggest going in the multi-use direction from the start. Get a 1/8" foam pad and one of it's many uses is under the tent as a ground sheet. Then a light/cheap inflatable pad (https://www.amazon.com/Sleepingo-Camping-Sleeping-Pad-Backpacking/dp/B07FP4Z3RZ/) inside the tent on top of it will round out the comfort/warmth equation for about the same price (later, when the ul bug strikes, you can cut down the inflatable to torso length, weld it shut with a clothes iron, and use your pack under your feet) But this is more preference than right/wrong compared to your list
You can absolutely piece together a Big 3 set for around $300 or less that'll be totally fine for shorter hikes in good weather. It's still worth avoiding no-name brands when you can, but here's a quick sketch of one: Kelty 20⁰ synthetic bag: $80, 3lbs 2oz ALPS CCF mat: $30, 10oz Ozark Trail 1p tent: $80, 4.1lbs REI Trailmade 60 pack: $125, 3lbs 6 oz This is already over 10lbs with just these items, so it's not exactly ultralight. However, this plus a cheap stove/pot setup, headlamp, and some items from around the house, and you're a good chunk of the way to a complete kit. The price skyrockets pretty rapidly once you start wanting to shave ounces, get more compressible insulation, or survive more extreme conditions. That's why mid-tier and top-of-the-line gear is so pricey, it's functionality at a lighter weight (plus relative lack of demand for expensive UL gear) that drives it up. If you don't know how much you'll use your gear, better to get something cheap at first, then if it wears out or you get sick of the compromises, you can always upgrade later. "Buy once, cry once" is only good advice if you already know you'll use what you're buying consistently.
For casual three-season camping around 0°C, synthetic’s way easier on the wallet. Marmot Trestles or Kelty Cosmic Down alternative bags hold up fine, and you don’t freak out about melting water or sweat ruining insulation.
First, I would say used higher end gear is in many cases better than new cheap gear. r/ulgeartrade is your friend and so is eBay and facebook marketplace. Second, the used versions of these will probably be better than new what you have… Naturehike 65L 40.96oz $120 -> this is really big, I bet you can get away with 55L if you really want to go UL -> you can get a used kakwa 55 for like $150, just make sure you get the right size Featherstone 20 Pad 26.3oz $109 -> neoair nxt, 16oz, three season all day, I got used on Facebook marketplace for $100 Ampex 2p 64oz $170 -> noooooooo. Used xmid 2p same price. Much better, half the weight at 32oz, if you want new than lanshan 2 Kelty Cosmic 20 Mummy 39oz $180 -> if you want to go UL, need to get comfortable with quilts -> new $230, used probably $180 -> https://hammockgear.com/product/burrow/

NEMO
Disco 15 Series
Spacious for side sleepers; bulky, temp rating optimistic.
Hammock Gear
Classic Burrow 20°F
Budget king; very warm but heavier than ultralight.

NEMO
Disco 30
Spoon shape for side sleepers; prone to zipper issues.

Western Mountaineering
VersaLite
Durable, very warm; premium price, too hot in summer.

Katabatic Gear
Alsek 22°F Quilt
Versatile 3-season quilt; secure pad attachment, high price.

Ranked #1
NEMO - Disco 15 Series

Ranked #1
Kelty - Tru.Comfort Doublewide 20
Ranked #1
Enlightened Equipment - Revelation APEX

Ranked #1
NEMO - Disco 15 Series

Ranked #1
Feathered Friends - Egret UL 20/30

Ranked #1
NEMO - Disco 15 Series