You can buy 3" lift kits like Skyjacker and Rancho for around $400.00. You will want a kit that supplies a rear add-a-leaf and not a block. You already have a factory block and stacking another block on top of that is a "no-no".
Generally speaking, 3" is the max lift you can put on your Ram and retain your factory length control arms and trackbar. You will have to have longer shocks in the front if you add either a 3" spacer or a 3" coil spring lift (3" longer than stock means you need 3" longer shocks......no way around that).
If your after 35-36" tire clearance, you will need 5" of lift to be able to offroad with it. You can get that rather cheaply by starting with your 3" suspension lift and then adding a 3" body lift. So for well under $1000.00 you can have 6" of lift.
As posted above, you can also just start with a 5" lift kit like Skyjackers or Fabtech's (I would stay away from the cheapy kits like Rough Country, Tuff Country, Superlift etc....). The good 5" kits will run you around $1200.00.
If your intentions are to be able to run 37-38" tires, then start with a 5" suspension kit and a dd a 3" body lift, or you could go with a long arm suspension kit llike Dick Cepek or Rock Krawler.
The choices are really endless for your Ram, but a good way to start is with a 3" suspension lift because they are relatively cheap, easy to install and they don't affect the drivability of your truck.
Then if thats not enough, add a 3" body lift and 35" tires next. If you outgrow that, then a 5" or 7" suspension lift plus your already lifted body will get you in the area of 37-40" tires.......like I said, endless.
Look on the classifieds for somebody else seling a slightly used 3" kit. That would be where the best value would be found.
Usually when looking at lift kits for Rams, the front lift will be 1" higher than the rear....so if you are loking at a 5" lift kit, the rear would be lifted 4".
Good luck to you and do some searching and reading and then get a kit and start modding!!!