I'd like to build one but i'm not so knowledgeable, i get lost in the options out there and had to make uninformed decisions and later wishing I did something different.
i bought an essential arms lower and a del-ton M4 kit
it has everything you need except a rear sight and mags/ammo
i spent 88+shipping+FFL fee for the lower
i spent 517 shipped for the M4 kit (only upgrade was the chrome lined barrel)
everything you spend above that is completely up to you
the accessories i've ordered so far are a sling attachment plate, sling, front sight tool, carry handle