I can buy an unlocked Galaxy S4 for £402 from Amazon, and then use a GiffGaff SIM which costs me £10 a month for an unlimited internet (inc 3G) plan which doesn't lock me into a contract because their margins are tiny compared to any other provider. Over two years this is only £642. Of course, if I did get it from a phone shop, it'd be £942 for the same time period. Still, this is a high end phone, and it's way less than what you said as a maximum.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 48GB
GPU: Radeon 7800 XT
CPU: AMD Ryzen 5900X
RAM: 48GB
GPU: Radeon 7800 XT