Your profile says you are from Illinios. My guess is it will be hard to find a vdrive for under 20 in the mid west. To get a v drive you are going to have to be willing to drive a long ways. California is your best bet. Here is a list of v drives you have a chance of seeing for 20k or less.
-Nautique 210 hull-probably aren't going to find a SAN but maybe a 1999 or 2000? They started making that same hull in 95 I believe in the form of the super sport. If you can find a 95-2000ish supersport they should be in the 15-20k range.
-Mastercraft 205v hull-probably wont find a v drive xstar but might find a 99 or 2000 205V.
-Malibu Sunsetter VLX-mid 90's to 2000. Might be able to find a 2000 wakesetter vlx(same hull).
-Tige 21v/2100v-these always seem to be in the 15-20k range. 99 is the first year and made till 2002.
-Sanger v210-should be easy to find on the west coast for that price. Great wake, great build quality, very efficient. Probably impossible to find in the mid west.
-Moomba Mobius V/kamberra-made from 2000-2003. I had a 2000 and it was an awesome boat for the price. can throw a great wake, easy to add ballast, simple, bigger then most the other boats mentioned. They don't use the thickest cushions or vinyl.
-moomba mobius v/outback v-might be able to find an early 2000's mobius v for around 20k.
Looks beat on and would need a tower
Nick Tomsyck from wakeworlds boat. setup pretty good. Interior somewhat rough if I remember right but sick wake. fUnny that the add says original FCT tower. I always though it was completely custom but it actually looks like the original FCT chopped down and attached to different lower mounts.