To anyone starting to gather tools to do a project, I would say look at the whole job, making a list of taps and dies needed. Forget fancy sets of drills, half will never get used. Ascertain only the necessary tapping drills for the taps required, listing them. This way, you will keep the costs to a minimum.
"Collect the set" started in schooldays with items like Robertsons badges or cut out pictures on cereal packets of servicemen in various uniforms and so on. Progress to later years where manufacturers play the same marketing ploy with sets of spanners in AF, BA, BSW METRIC etc and sets of screwdrivers, pliers, tweezers and of course, umpteen different tap and die sets. Boxed threading sets also contain a tap wrench and diestock, useful first time around but why would you want to duplicate them with every boxed set that you buy?