A lot of the basics you can buy for a lot less money than Park charges. With the basics, like allen key sets and metric wrenches and socket set, out of the way you can buy the Park or Zefal tools that you need rather than a kit that will have some stuff that you may never use. For example if you never need to do a threaded headset you won't need the big flat wrenches that are needed for them. And if you just buy as you need then you can build up the kit slowly and with some added focus.

A few things that you SHOULD get right away would be;

• All three sizes of spoke wrench. Get the nice plastic dipped ones.
• The flat cone nut wrenches used for cup and cone wheel bearings.
• A BB tool to suit your bike(s). Although this can be put off until you need it.
• Crank arm remover. Again it can be put off until needed.
• Thin pedal wrench.
• Tire irons of course.
• and the basics, metric allen key set, metric wrench set from 8mm to 19mm. And a 1/4 and 3/8 combo ratchet set isn't a bad idea as well.

For a fairly new bike with threadless headset and a square taper style BB setup this is about all you need to work on the bike besides the more normal handtools that most home shops would have anyway such as assorted screw drivers, pliers, cutters, etc. If you don't have ANY of that stuff you'd need to expand a bit on the list above to fill in the missing links.