Right now dedicated graphics cards are just ridiculous in price. I wouldn't even bother trying to find a new GPU at a good price. Obviously if you have a budget that allows you to spend ~$600 on a graphics card then you could probably find a decent GPU from a scalper. But, the good news is that you can get ok gaming performance from an APU. It will be a ton better than your current machine!
Here's a cheap budget build based on the 5600g APU from AMD that will be much better than your old system:
PCPartPicker Part List:
https://pcpartpicker.com/list/Zd9c8J
CPU: AMD Ryzen 5 5600G 3.9 GHz 6-Core Processor ($242.49 @ Amazon)
Motherboard: Gigabyte A520M DS3H Micro ATX AM4 Motherboard ($70.98 @ Amazon)
Memory: Crucial Ballistix 16 GB (2 x 8 GB) DDR4-3600 CL16 Memory ($77.16 @ Amazon)
Total: $390.63
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2022-01-20 12:40 EST-0500
I didn't include storage or a PSU. Feel free to get a better motherboard - the one I included above is inexpensive but it does allow you to update the BIOS without a CPU installed.
Here is the review of the 5600g:
https://www.tomshardware.com/reviews/amd-ryzen-5-5600g-review
The 5600g is a six core CPU that packs the newest Zen 3 architecture. In the future, if you decide to put in a dedicated graphics card, the 5600g is powerful enough to drive it very well.