This Featherstone 2 person backpacking tent is pretty good for the price. Good headroom. You’ll probably want to store your gear in the covered vestibule rather than inside due to space.
Featherstone Backpacking Tent Lightweight for 3-Season Outdoor Camping, Hiking, and Biking - Includes Footprint, Waterproof, Packs Light and Compact https://www.amazon.com/dp/B0727Y4XLT/ref=cm_sw_r_apan_glt_i_37SSVQYVK8QWNE2Y2E2E?psc=1
Double wall 3 season 2 person tent. 2 doors 2 vestibule. Comes with a footprint. Great great beginner tent.
I agree with this Cheapest solution would be a walmart blue tarp made into a A frame with trekking poles and tent steaks at REI.
FeatherStone sent me a Tent to Test out. I'm near Tahoe, which is similar in elevation and weather to Philmont. It is verry affordable compared to other Tent makers and SO far i've been impressed with it.
It's 3.8 pounds and $112
-split between 2 people and it's as light as most Ultralight trekking pole tents for each person. Gear review post in the making.
https://www.amazon.com/Featherstone-Backpacking-Ultralight-3-Season-Expeditions/dp/B0727Y4XLT?th=1
You're going to get a lot of comments about going truly ultralight. And yes, spend time in /r/ultralight to gain knowledge. But I think you're more just asking how to get a decent (not truly UL) setup for less money.
You should be able to get around 15 lbs. pretty easily. The best way to do that is to focus on your "big four" — backpack, sleeping bag, sleeping pad, and shelter.
There are knockoff Big Agnes tents out there. If you like the Big Agnes Tiger Wall, check out tents by Featherstone (https://www.amazon.com/Featherstone-Ultralight-Backpacking-3-Season-Expeditions/dp/B0727Y4XLT/) or Lanshan (https://www.amazon.com/Ultralight-3-Season-Backpacking-Lightweight-Trekking/dp/B09Q31TJ95/). The former is a Tiger Wall knockoff, and the latter looks like a Gossamer Gear The One knockoff. Yes, the Featherstone is 4 lbs., far heavier than the 2 lb. weight of a Big Agnes Tiger Wall UL2 Platinum. That said, it is $139, not $650.
I'd also consider investing in some of your hiking kit that you'll use later. For example, a decent 10 or 20-degree quilt is going to be necessary no matter what, so maybe you splash out out an Enlightened Equipment quilt or similar. It's not like quilt/sleeping bag technology is moving that quickly.
Then there's used gear sold here on places like /r/geartrade... just be careful of scammers (insist on PayPal goods & services).
Just some ideas for ya. Good luck!!