I just upgraded my PC with used parts about 6 months ago with the intent of using steam OS Linux on it when it was released officially. I paid $150 for a ryzen 5 5600x CPU and $200 for an AMD 6600xt GPU that has rdna 2 (same as steam deck). Other components to build one from scratch should cost you like $600 more if you had nothing. Less if you find used stuff. But yeah. No tiny form factor and you won’t save that much. Especially that the ram and hard drive in the steam box are easily upgradable, so you can buy the cheapest one and deal with those getting upgraded later after the ai bubble bursts.