your post raises more questions than it answers though.
Do you know how to fix and maintain motorcycles? Dirt bikes *usually require more maintenance.
Do you know how to shop for dirtbikes or at least watched youtube vids of it?
I'd suggest anything Japanese for reliability (Honda, Suzuki, Yamaha) and availability on old parts. Especially for something you may want only temporarily.
The cheapest isn't usually the best if you don't know what to look for.
And with 2k, you're about to be finding only basket cases. So my next question is do you want to ride all day without needing tools?
if no, then you're limiting yourself to a 125 or some very old dual sport maybe. If yes then buy whatever fits you.
If in 5 years you're still riding dirt, by then you will have a much deeper awareness of what to invest in.
Now another point is the current national emergency. Will you be able to get parts from ebay or amazon (via China) for this bike?
Will a sub 2k used bike even run well without further investment?
These aren't exactly lawn mowers. They will take you miles into the wild and you may be pushing it back to your truck so on a few chaotic factors I might even suggest to use the 2k and buy a last years model at the dealer. Say a trail 200 or even a 250 four stroke.
This would maximize your ride time and possibly eliminate any unforeseen repair problems while you learn a strict maintenance routine and learn the bike. The new yamaha 250 is incredible but even a new 125 will be more than capable of filling your day with fun.
In fact, I've had much more fun on technical trails on my super old 125 than my brand new yx250fx (and I'm 6' 190-220lbs (depends on holiday food)). So if you ask me what bike I would buy myself in your situation, would be a new (*last years unsold model at a dealer) 125 or 250 four stroke and make payments.
It will hold its value for at least a few years and you won't be in the problem of buying a 2k basket case that needs 3k in parts (which you might not be able to get).
Hope that helps and even if you get a mountain bike (bicycle)...happy trails.