Something like this would be a starting point.
You could price out something similar from somewhere like memory express and have them build it for you. $955+tax,shipping,Windows.
the issue is, for a bit of extra money there are improvements that could be made. But if keeping cost down is a priority, that would work.
Personally I would +$50 for a better motherboard, +$90 for Ryzen 3600, +$50 for a better case, and $20 for some faster ram, and $30 for a 650watt version of the power supply...but that does add up. Potentially a used graphics card to save some money.