The initial cost might be less, but I doubt the final outcome with an S-10 frame would be near as nice as updating the suspension and brakes on the original frame. Don't forget the labor part of the swap, changing body mounts, rebuilding the box to accomodate the kickup on the S-10 frame, reconfiguring the front sheet metal and radiator support to work on the S-10 frame without having it look like a cobbled up mess, getting the inner fenders to fit the S-10 frame, altering the wheelbase and track width to make the wheels fit the wheel openings, and a multitude of other things to make it look and work right.

or, If you don't have the time and money to do it right, when are you going to find the time and money to do it over?