A Mychron4 or 4t with a Data Key plus an IR beacon to record and analyze lap times. A big step up would be an M4 with GPS. This would give you the ability to plot and compare each lap graphically. Also a Go-Pro camera might be helpful. Will this affordable? Only you know how big your wallet is. But no matter what, you’ll need a Mychron and you can read the lap times and temperatures off of the display. Keep an eye on the Classified section on the forum for a deal.