CPU: Intel Core i3-4130 3.4 Ghz dual core
GPU: Intel HD Graphics 4400 (Built into CPU, Planning on getting a Sapphire Radeon R7 260X 2GB at a later time.)
RAM: 4GB Corsair DDR3
Motherboard: ASRock H81M Micro ATX LGA1150
HDD: 500GB WD Caviar Green
PSU:Corsair Builder 600W 80+ Bronze Certified ATX Power Supply
Would this be good for gaming (Without the Radeon R7)? Would this be a low end or mid end gaming rig (With the Radeon R7)? What end would it be without the Radeon R7? What fps could I get (With and without the Radeon R7)? And is there any other GPUs or CPUs for around the same price that are better?
Without the GPU, expect VERY lowest settings in any and all games and expect demanding games to not run at all. With the 260x expect most all modern games to run comfortably at medium settings at 1080p.
Change the PSU to an XFX 550 unit as it is WAY better quality. Change the HDD to a Blue or Black from WD as the Green drives are slow and designed for servers.
I'd save up a bit more bud, Intel HD graphics are terrible for games, a faster hard drive would also be advisable. For your budget I'd go with an AMD APU but if its upgradability you want then save up more so that it can be upgraded well.
Oh yeah, some games playable with Intel HD graphics 4000: