Not sure what is in the "kit". I bet I could come up with $120 of stuff if I tried, but that does not mean it is all in the kit. Normal stuff would be 3 1/4" bolts, 3 1/4" nuts, 3 1/4" acorn nuts, possibly 6 1/4" washers, a Weber grate (and many double all of that and install 2 grates). Normal build has 3 3/4" close pipe nipples, 2 3/4" caps, a 3/4" ball valve, 6 3/4" conduit nuts (but some people just use magnets to close the holes). Personally I preferred brass nipples and plugs, they cost a bit more but are less maintenance - but then again now I use a guru and that is a completely different story.
The fire basket takes a decent chunk of expanded metal (I think I made 2 from a half sheet - but you can use a bit less if you use a donated charcoal grate), then you will normally want an ash pan. You will also want a pit thermometer. I also have a few valve stems on mine to act as gourmets for temp probes.
The top has a bunch of options, depending on your drum. If you use an open top, you can just remove the bung hole and screw in a smoke stack (and something to cover it) - or drill a few holes (arghhhh, all the rain will come into your barrel). Many people prefer a Weber lid.
Then there is building equipment - step bits and burner. Kit probably does not include this $40-50 of stuff.
Oh, did not mention the basket handle. I like my system of a re-bar chicken's foot. The base is below the ash pan and the leg goes up through the basket. Grab the leg and the whole assembly lifts up, plus the feet give some insulation between the drum bottom and the ash pan - but it requires welding.