Regarding the adapter, you have stated that they're expensive. Do active or passive ones cost anywhere close to an acceptable monitor? If so, how much? Is there any loss of quality when using an adapter, or is the loss just because of my monitor?
Passive adapter, which just takes one form of connector to another, essentially costs peanuts.
E.g this DP to HDMI is 8 bucks,
amazon:
https://www.amazon.com/DisplayPort-Gold-Plated-Avacon-Display-Adapter/dp/B01FX3K7T2
You can find them cheaper too.
Active adapter, on the other hand, has to have "brain" inside it, to transform digital to analog or vice-versa. Thus, inherently, they cost more.
E.g this DP to VGA, which costs 5x times more than above adapter, at 40 bucks,
amazon:
https://www.amazon.com/Accell-B101B-003B-DisplayPort-Active-Adapter/dp/B003HC85D2
Monitors start as low as 70 bucks,
pcpp:
https://pcpartpicker.com/products/monitor/#sort=price&page=1
You can find monitors on 2nd hand market even cheaper, if not completely free.
As of what is "acceptable monitor", is individual.
To me, and the fact that i can buy brand new monitor, at the cost of ~2 active adapters, makes the active adapter expensive. If the active adapter would cost ~20 bucks, then it would be more reasonable. But then again, the "brain" part of it, at ~20 bucks, may be substandard or not work at all.
Quality loss wise, it depends on how good the active adapter is. If it's cheaply made, there most likely will be quality loss. Well made active adapter costs more and here you need to look at what point the price is "too expensive" for small active adapter.
I haven't used any active adapters to tell from experience. Closest i've used, is DVI-I to VGA, but DVI-I already carries analog signal in it, so the cable i have, is passive adapter.