My bargain basement version:
A Samsung S3 i've built in to my dash, running the Racechrono app but with the paid for OBD2 and laptime 'addons' (about £5). OBD2 addon accesses linking to a £5 ELM327 bluetooth module - logging the revs/speed/throttle position for doing the video overlays. Laptime addon gives live delta time for instant updates on ongoing lap. Needs a 10hz GPS receiver for timing accuracy (1hz all phones have on GPS is pants), i use a Qstarz version, which is about £70 new, and half that if you can wait and hunt for a used one.
Can see it working here:
(pan down to see the phone, its where the clock usually is, can also see GPS mounted by screen vents.)
and overlay data looks like this, when run through Racerender software.:
However if you have deep pockets a Vbox setup will do all the above in one pretty much. But way in to 4 figures.