If I could only fly 1-2 a month due to work, is it better to buy a plane or just join my local club?
Here's my .02
100 hours per year would be the decision point for me. A more liberal number may be 50 hours per year. So let's go with that instead.
We'll just forget the acquisition cost.
I have to think hangar rent in that area of NJ is around $300 per month. There's $3,600 per year
For insurance, let's just go with an easy number like $1,000.
100LL for 50 hours at $4.00 a gallon and 8GPH would be $1,600
So at this point we're at $6,200 per year.
It would appear that around $125 wet is the going rate in that area for a 172. Which gives you $6,250 for 50 hours. A coin flip decision... although we haven't figured in maintenance or acquisition cost.
You're only going to be flying 12 - 24 hours per year. Which means you'll spend more on hangar rent than you would renting a plane.
The other (and IMO, greater) factor is the toll on not flying (a hangar helps... some). If the plane isn't flying 50 hours a year, the airplane is not happy. Stuff seems to fail more often than when it flies at an hour or two per week. That's its way of telling you it's not happy.
So (once again, my opinion only) I think based on the number of hours you're thinking about flying, renting is the clear choice over owning. You can schedule in advance so availability shouldn't be a problem.
Now here's an alternative (although it is a bit of a long shot): I had some times where I wasn't flying much. Rather than have the plane sit for long periods unused, I let one of my old instructors fly it for personal use. All he had to do was cover fuel. (he offered to pay extra, but I didn't like the potential of "rental" that could be an insurance problem). I knew him, he knew how I liked the plane to be flown and all the little idiosyncrasies about the plane. He was happy because he had access to a plane that he could use to fly and see his daughter about 2 hours away. I was happy because the plane wasn't sitting. He met the open warranty on the insurance policy but even if he didn't, it would have been easy to add him to the policy. So maybe ask around the local airports. You might find someone with a plane who would like it to fly more. I know that if I hadn't had my old instructor, an airline pilot would have been a nice alternative.
I wouldn't do a leaseback to offset the cost and keep the flying hours up though. I did that for about 3 years. No way I would do that again on a plane that I flew.