The Jack can be made to lift to varying heights, as standard the dimensions in the plans allow it to lift 12inches,
For my own jack I,m going to make 2 lifting height levels, 1 to be just enough to raise the wheels/tyres off the ground ( allowing for suspension droop etc ), & another to raise it high enough to allow axle stands to be placed under the chassis.
Not sure on cost, I,ll make mine & see what it costs in materials etc.( not alot), Tho I,ve seen others for sale at £100 plus
cheers
andy