Yeah, last time I looked, TTIs were in the $800 range. In my case, I sold the early 340 manifolds I had on the car for enough money to buy the TTIs.
Installing the passenger side TTI header was pretty straightforward. Had to move a few things around on the driver's side (mostly brake lines and electrical wiring, with slight mods to the clutch linkage). Despite all that, I was impressed with the fit. The early A body engine compartment is significantly narrower than the 67-later. Narrow enough that even factory exhaust manifolds and head pipes are difficult to fit.