Well I did buy recently. I first had a 220 point contract at $54.50 plus closing and paying only a prorated amount of fees which
DVC bought back under their ROFR. I then had a contract which went through at $54 per point. Note it had no current points but all 333 there for December. Seller paid both closing and Title and since there were no fees until December, I had no maint fees to reimburse either. At that time the buy back was reported at $58 per point. That was around the time when the price was going up. We submitted to DVC before the price increase but only shortly before. I've heard rumors of $62 with the price increase.
My experience and other info I've gathered shows DVC to be schizophrenic when it comes to the ROFR issue. They sometimes buy back things you think they wouldn't and at other times let through contracts you are sure they'd take. In general larger contracts with less available points go through at lower prices but we're talking 300 point or more. Also, it appears that seller paying closing, etc tend to make DVC less likely to buy it, the reverse should be the case based on $$$. I've also seen them allow a contract less than 150 to go through to someone who was not otherwise a member, I've seen this twice.
Smaller contracts, esp at BW, BC and WLV will likely be more likely bought by DVC. The resale agents should have the most info on what DVC will allow but they can only tell you what they feel based on their experiences. Once upon a time DVC would allow you to submit a higher offer but these times seem gone.
As for VB, I think the price will tend to be cheaper on resale than at WDW, same for HH. Whether it's worth it to go resale for a small contract at VB depends on your situation, how many points you want and how willing you are to walk away. With MB, the price per point is around $67-69 per point ($15 MB + the maint fees). For 100 points, that's only a savings around $550 ($10 pp difference and add the closing costs). If you have to pay more maint fees than through DVC, the difference could shrink to as little as $350 or so assuming the MB and a resale price of $55 pp. Of course you might get a contract with a lot more points than you'd have through DVC AFTER the MB sell back or you might not. You also might be able to negotiate better terms, as I did. BTW, my offer was take it or leave it and I WAS WILLING TO WALK AWAY. The seller first said no and when the broker called me, I said ok, thanks, see you later. I even told him he could look for another contract if he wanted but not to really worry about it. Keep in mind we'd already had one bought back. I think he called the seller back and told him I was gone and he changed his mind.
That brings me to my 2 final and main points. 1. The price difference for an add on is rarely worth sweating the difference for resale unless you can take it or leave it. 2. Each contract much be evaluated indepently as to price, fees, points availability and the like.