assuming all in 2k, monitor ~$250, mouse & kb ~$50 means the rig itself about 1.7k, which is quite pricey. not sure if bcos got extended warranty. when gpu prices were more sane before the 30 series launch, u could probably diy a rig like that for about 1.4k with actually good quality parts. anyway, see if possible to downgrade to 10600f, u probably wont be using those extra 2 cores if only gaming. 10400f is kind of pushing it since the frequency drop is quite substantial; 10600f and 10700f share the same boost clocks.
no. in fact u wont be getting ur money's worth, since:
a) costs more than the dell one while using a (slightly) inferior gpu
b) uses a kf processor but with a b460 rather than z490, so the premium u pay for overclockable cpu is wasted since b460 cannot oc