If it will save you money, why not? There are a lot of things one do without because they hardly ever use them though the need might arise at some time. For example if you don't have to do any repairs on your house regularly, there wouldn't be any need to buy tools. Should the need to do some repairs arise then if your neighbor has the tools required, you can always borrow. Now apply that to everything. If you can borrow it, don't buy it.
Oh I do this all the time, and Facebook makes it easier than ever. If I need something (especially baby and kid items) and know I won't use it much, I go to Facebook first and see if any of my friends or neighbors has it. More often than not, multiple people do. But I also belong to a few Facebook swapping pages. Most of the posts are put up for permanent trades, but many of them are things people are just giving away, or looking to borrow for a short time. I love saving the landfill from one more piece of junk that multiple people could easily use.
I think its a great suggestion, but the problem is not everyone has good neighbors. And, honestly, I don't have a personal relationship with anyone in my neighborhood (when we moved in no one came to meet us or anything, though I guess I didn't get introduce myself to them either), so it would be very strange for me to knock on their door and ask to borrow something. However, I do think its a great idea if you have a great neighbor!!
If I'm just going to use it once or twice then I do strongly consider just borrowing or renting it. For some though, I always calculate it and sometimes I end up figuring out that I'll probably just be better off buying one. For example, I had my house painted once before and the workers needed a spray paint machine, and seeing as I knew I'd be needing it often with all the other remodeling I planned to do, I just bought one instead of renting one from their employer.
Honestly while the idea is convenient, it's rather reflective of dependency in one way or another and I'm the independent type. I don't like asking to borrow materials, let alone ask for favors. I'd rather buy it myself or do it myself unless I just can't. Just because you might appear to have nice people apparently willing to let you borrow something doesn't mean they are cool with it either. They could be wishing in the back of their head that you just buy your own and stop calling for their materials to borrow.
I've thought of that too, but I'm quite shy to ask our neighbors, so I end up buying the equipment that I need, even if I'm only gonna use it once or twice.
