Pretty sure people would be very interested in seeing "Cheapest Amazon PC ... that doesn't suck". For $304.72 USD with a mix of Amazon and Newegg pricing, I put together the following build list with all-new parts. I believe it would perform wonderfully as a basic office machine, HTPC, or even 'granny's rig'. Would love to see you build it, or better yet, come up with a better "non-suck" build for around the $300 pricepoint.
CPU: AMD Ryzen 3 2200G
Mainbaord: ASRock B450M-HDV R4.0 mATX
RAM: 8GB (4GBx2) DDR4-2400 GeiL Evo Spear AMD Edition
Storage: 1TB Western Digital Blue 7200RPM
Case & PSU: Rosewill R379-M Slim mATX Case(Comes with 300W Rosewill 80+ PSU)