Non Stretch Rope/Fat Sack

My dad bought a 2001 Super Air Nautique, and it comes stock with whatever ballast it had. We also only have one rope, which is a slalom rope. I have mastered switch, and did a wake jump with the slalom rope, hard as heck to get that progressive edge. I think i am at that level where i would benefit from a non-stretch rope. What would be a good, relitivally cheap non stretch wakeboarding rope/where to find it? Also, because our air nautique only came stock with 500 pounds of balast (i think), i have heard alot about fat sacks, and was thinking about getting one for our boat as well. I was thinking about a bow sack, or one you put in the ski locker (v-drive?) because we have slalom racks on our tower anyways. Thanks for the help!