As the price of the kit goes up the level of travel that it is able to acheave goes up (usually)
The basic 5.5 XLT kit for $1800 is what I have on my truck that you saw Sunday. Its a fairly simple bolt on system. Nothing all that extreme, good mix of offroad ability and daily driver use. The key reasons to get this kit is to replace the upper ball joint and the forged spindle. You can upgrade the system to use 2.0 adjustable reservoir shocks at a later date (when you save up more money).
The Long travel XLT kit for $3800 requires quite a bit of work to install. Namly removing the coil bucket and smoothing out the frame, which we talked about. That basicaly lets your XLT use an Edge style system. The advantage of this kit is that you can use coil over shocks and replace both the upper and lower ball joints with uniballs.
The LT Race kit for $5500 gets you everything the LT kit comes with but with all the upgrades: better hubs, brakes, billet upper arm, coil overs and bypass shocks and so on. That way you can run bigger tires, better rims with a stronger bolt pattern, and have brakes big enough to stop you. If you truely want to "Race" baja like you mentioned it would be a good kit for you. However if you just want to finish and do the drive then the it might be a bit over kill.
Remember that shocks are not included in these kits with the prices I listed. Thats why the Long travel XLT kit has two prices on the site the 3800 for just the kit and 5800 with all the goodies. Getting it all from Camburg can be good since you know it will work but if you want to fine tune the set up you can buy the air bumps, coils, and shocks on your own.
Hope that helps. Keep the questions coming.
Andrew