Here's the beautiful thing about Datsuns (especially the older ones): they are super easy to work on. If you're slightly mechanically inclined at all, have a bit of passion for cars, and a bit of determination... You can get it to run.
It's still a 40+ yr car though so there's going to be some challenges. There's probably going to be some rust, parts are going to be harder to find, and depending on where you live, there may/may not be any Datsun specific people to help you.
If you scrounge up the cash and pick it up, this community is here to help. We won't hold your hand, but we will guide you in the right direction to building a great car you can be proud of (if you put in the work). There's many younger members here so just because you're 16 doesn't mean you can't learn. Starting young is the right way... I wish I started wrenching that young. What that means is that your build just might be slower due to a shortage of constant funds.
It's all up to you.
I will thank you for posting the contact info for the owner. If you can't pick it up, hopefully someone local to you can. Wagon looks like a great project for someone to save.