Okay so for the SAS info I do know offroaddirect.com makes a 4-link swap kit. It's about $1,300 or so for the kit. After that you will still need front axle, shocks, coils, tires, sterring set up, and a 14b if you don't have one already. With the coil set up I know it is pricier and if you are paying a shop to do the work it will go up more in price.
If you want to save some money SAS with leafs still gives you a solid platform to start with when wheeling and driving on the road. I get plenty of flex with having leafs and I like that it feels more sturdy going down the road unlike coils witch roll and are a more cushy ride. But just do plenty of research and you will find something you like