I would say 150 is not, because I rarely hear of anyone sticking to just a studio for their entire ownership. Not to say that some don't do it and stretch it and are fine, but over and over again you'll hear to buy more, that lifestyles change, you get the itch for privacy and saving money with a kitchen and packing less with laundry in the room, you can fulfill a wish bringing X person or Y kids, whatever.
As well, since you're buying in now, the promotions are pretty good for VGF. Even bumping up to 200 would net a better price that you won't be able to match later on. If you can swing it, I think 250-300 is best, but that's a sizeable chunk of change and may be overkill for your first few years. If you DO get a larger sum of points, be sure to break the contracts into 150 and then 50s or 100s in case you ever want to sell off some points (at a nice profit, most likely,) in the future.
The only caveat to needing more points if you think you'll be okay staying at lower point resorts. If you love GF and Riviera, they're very high in
point charts. If you want to sleep around, 150 should do very well.
Congratulations, and welcome home!