If you are looking for a one time stay, you will need to contact a member directly and set up the details. We have a "Rent/Trade" Board here on the DIS which is designed to put Members and potential renters together. All details of the transactions are between the renter and the member.
If you looking to Buy into DVC, you can contact DVC directly or one of many timeshare brokers. TO buy into DVC means you will buy a specific amount of points. These points will be renewed each year on your "use year" date until the year 2042. These points can be used to aquired accomodations at each of the DVC resorts or be traded out for other accomadations.
As for how much do each of these options cost. Well it is all dependant on when you want to go and what size room you will be needing.
DVC is Disney's version of a timeshare. You buy points for a certain price (currently $84 per point) and then you get a new allotment of those points each year until 2042. You can buy points at any of the DVC resorts and you will then have an 11-month window to make reservations at that resort and a 7-month window to make reservations at the other DVC resorts.
If you are looking to get points for a 1-time trip then you will want to rent points. You can check the DVC Rent/Trade board on this site (located right under the DVC Forum) for someone who is selling points.
You can also book a stay at Vero Beach for cash, just as you would at any other hotel.