I'd also like to add age and condition of the vehicle also come into play. We all throw around how easy a lift spacer kit install can be and although they are a cheap to acquire kit and a fairly easy to lift to install on a well preserved trucklet. A not so well preserved normal/average condition track kick is where the install of any lift can and will in fact bleed you of money.
Understand the newest 1st gen track kick is now 12 years old (the 1st gens stopped production in 1998) Mine is a 1995 so it's now 15 years old and i live in snowy Michigan so pretty much everything under the car is rusted. I bought Jeff's kit and it's excellent for a great and fair price. But to no fault of Jeff at all there was considerable cost above and beyond Jeff's kit in order to lift my track kick.
It's not as easy as buying it and slapping it on. most can't just jack up their car and install it with basic tools. It can be an incredibly long, nerve racking, and pricey install. You are not usually done spending money after buying the kit.
Being a decade or more old these trucks usually have considerable rust on their suspension components. In my case I had to get replacement tie-rod ends from Hawk because mine on the truck were so rusted and fused i had to practically melt them off (well really I heated them cherry red and bang away at it till they loosened...but either way they were ruined)
My sway bar was so rusted that it flaked away to nothing in my hands. The bolts were fused solid from rust. Again i had to heat them up and needed to replace them.
My strut mount bolts were also critically fused solid from rust. I again heated them up and banged them loose.
Then there is the cost of new struts. And the tricky part is rear shocks. With the spacer kit installed you now need longer shocks and they are not usually direct bolt-on replacements. The Crown Vic shocks everyone loves need the lower bolt grommet drilled out and the grommet from the oem shock pushed in.
And after you do all this you will still save $100's of dollars installing a spring spacer lift kit over a pricey Australian spring and strut/shock kit. But, you will work much harder to install the coil spacer kit and still spend a couple 100 dollars in additional parts. So the cost savings are off set with hard wrench work. Which if you have the garage space and tools it's not bad...but if you don't? You have to pay someone to do it and it will cost you...dearly. This is not to discourage anyone from doing this or any lift but to just point out hidden issues a novice track kick owner will hit when installing a lift kit on our aging rigs.