Orky15.
It <i>used to be</i> that a new member buying in had to buy a contract of a minimum of 220 points. Several years ago they changed the minimum to 150. Although, there has been discussion about some new members buying contracts smaller than 150 points via the resale market, and Disney let the sale go through. But, if buying from Disney - I'm pretty sure Disney requires a minimum purchase of 150 pts for your first purchase.
Once you've "bought in," you may purchase add-on contracts for less than 150 points at any resort at which there is availability.
And, though <i>some</i> people have had success at purchasing small add-on's at BWV and OKW following their official "sell-out," it doesn't appear to happen very often, and several have reported being on a wait-list for QUITE some time before the contracts became available. So, don't count on purchasing at VWL once they're offically "sold-out," unless you're willing to wait a long time... (or hold out for the a small contract on VWL to come up on the resale market...)
So - if you're wanting to purchase less than 150 at VWL - you <i>could</i> do this now, prior to sell-out, if you'll go ahead and purchase at least 150 at another resort, first. (from Disney or resale)
FWIW.