The 150 points minimum is a DVC sales rule- not a requirement for membership (Disney itself has lowered the minimum several times). Some have suggested that Disney will repurchase the contract if a non-member offers to buy, but I can't recall anyone actually posting that they lost a resale purchase because of this.
If the offer is low, DVC will certainly exercise the right of first refusal, but I can't imagine that happening if the offer is high enough.
Why not make an offer and let us know what happens!
Enjoy!
My first DVC purchase was 100 Pt BW contract I bought as a resale in 2/2001. I paid roughly the same price per point as all larger contract were going for.
Disney did not care, as a matter of fact my guide at the time was able to look up the contract to check on the remaining points and use month prior to my final close on it. He was checking because he wanted to sell me add-on points with the same use month.