For up to 4 rods I like to use the Offshore in-line boards, these run in the $25 per board range, you can add accessories like the tattle-tale flags or other releases that add considerably to the price.
For more rods I prefer the tethered boards with a mast these may be purchased or ya can make a set fairly cheap. But these tend to be more costly than the in-lines. You will also need a bunch of releases with this set-up that also can be homemade or bought.
If ya just need something to get the lures away from the boat ya can use yellow birds or other cheaper in-lines they'll get the job done although some of these boards are not as efficient in rougher water.