Here's what I understand, please correct if someone knows different...
The sensor is the same in all products.
If you want to try and use the free DIY software on this forum,
then just get the basic Spyder2Express version for about $70,
otherwise you need the full SpyderTV Pro program thats $500-$600,
or you can go all out and get the Colorfacts program for $2400
Difference is the software and the higher TV Pro priced package also gives you a tripod adaptor for the sensor.
The TV Pro package is the easy way to go,
it will tell you what adjustments need to be made,
but I think only works on a couple gray levels,
the full Colorfacts program uses 10 IRE levels.