I'm wondering what is the cheapest gaming desktop/laptop that i could buy?

First off, a desktop-tower will be higher performing than a laptop for the same amount of money spent once over about the $400 level, or about $500 including the monitor and amplified speakers.
And, although old games like Minecraft need very little, and GTA V, now considered old as released April 2015 about 31 months ago, can play on low settings, you should really want a PC that at least approaches a decent gaming console in performance. You should want something that can play every game at least on low settings on 1920x1080 instead of digging out whether a game will even work.
I'm not talking $1000, but neither is a finished unit at $300 where you belong with a used console and rented or used games.

I'm not a gamer, but have extensive hardware and pricing for performance skill at what can be done. I can use web sites and youtube demos as well as any gamer.

One good path is buying a used standard desktop PC and adding a graphics card yourself. That's not as easy as plug in and run, but you seek performance for the price and the right choices get you great results.
You can start with a Dell Optiplex 7010
https://www.newegg.com/...5YV5U41673
or item N82E16883159930
with i5-3450 or 3470, 8GB DDR3 RAM, and 1 TB HDD with a legal valid Windows 10 Pro, known to use a standard power supply and fairly standard motherboard, delivered at $280.
Upgrade with a decent graphics card $70 to $150 where the graphics card will determine gaming performance.
https://pcpartpicker.com/products/video-card/#sort=price&c=379,380,377,394,395&X=0,15000
Watch the need for a PCIe 6 pin connection needed directly to the power supply since that would require a power supply upgrade.
At $350 to $430 get an AMD RX 550 2GB to GTX 1050 TI 4GB running gaming PC.
Gaming to Graphics processing:
https://www.notebookcheck.net/...849.0.html
Rank #100 at the low end and #58 at the top end (GTX 1050 TI 4GB)
40-50 frames per second GTA V on HIGH Preset to 33-40 fps ULTRA present is the range.

If you want to buy a complete gaming pc as-is new,
Newegg starts at $518
https://www.newegg.com/...erSearch=1
OPEN BOX RETURN FX-4300 (3.80 GHz) 4 GB DDR3 1 TB HDD AMD Radeon RX 460
The FX-4300 is not nearly as good as the 3rd gen quad core i5. 4GB instead of 8GB RAM. RX 460 is slightly better than RX 550. $518 gets lower performance overall than the $350 modify yourself.
Optiplex 990, they want $548 for a weaker CPU, adding Wi-Fi, a little better hard drive, gaming at a $410 level of upgrade yourself.

Bestbuy at $506 plus tax
https://www.bestbuy.com/...Id=5615009
AMD FX 4300, 8 GB ram, 1TB hard drive RX 460 graphics
RX 560 at $550
Into $700 at Best Buy for Intel quad core i5 and a decent graphics card.
$500 at Amazon
https://www.amazon.com/...0725PFQ48/
performs at the $350 level of upgrade yourself.

GTA V is playable on lowest settings on a laptop 1366x768 at the $330-350 level as i3-7100U Intel integrated

https://www.bestbuy.com/...Id=5835852

Looking at i3-7100U to i5-3450 and Intel HD 620 to even RX 550
http://www.game-debate.com/...U%202.4GHz
http://www.game-debate.com/...620-mobile
The $350 upgraded desktop is massively stronger than the $350 i3-7100U laptop.
Laptop gives you wireless Wi-Fi (can be added for $20 to desktop), a display, and ready as is.