All resorts prior to Riviera have and will continue to have the right to trade into the old resorts. It is only with the Riviera and future resorts that on resale that you are limited to that resort only. Now. if you only want to buy resale, since you won't be getting any of the Disney benefits except for transportation to and from the parks and free parking at the resort. I think you should look into Bonnet Creek, it is much cheaper than any DVC on resale. I own both, but at the current cost of DVC being over $100 a point on resale a 100 point contract still costs over 10k. You can buy a nice contract at Bonnett Creek for under 1k and the maintenance fees would still be lower. Now, I love DVC so much I have 425 points but I also have lots of Wyndham Points. I find my Wyndham points give me more benefits at a lower cost than DVC does, so since they have so many more resorts and locations than DVC does, I can't justify adding any more DVC points but am considering adding more Wyndham Points via EBAY.
Almost forgot. Be very careful of buying a resort whose Right To Use ends in 2042 if you think you may sell it in the future. The value of points that will end in 2042 will only have 10 years left in 2032 and their value will go down significantly the closer it gets to 2042. The tripping point hasn't come yet but it will come and sooner than some people think. If you don't care and will use it, and really want DVC resale is the way to go. Consider an Old Key West 2057 or another resort with a later end date.