Here's the way I view it. If you're buying a tool to rely on in a business, you need reliability. If you must have reliability, you buy new--especially with something as inexpensive as a saw.
If you're looking for a personal saw for recreation or whatever, then you might buy used. However, if you buy used, you're looking to save money. Paying 5/8 the cost of a new saw for something that is decades old is not saving money. You're investing in something that will not last as long or hold its value as well as a new saw, and will likely need more fixing.
So, in order to save money, which is really the only reason to buy used, you need to find a saw for cheap. (I came up with that one all by myself.) That means, in turn, that you need to make any major repairs yourself, if buying from a dealer, or get lucky in buying from an individual. Buying a used saw from a dealer is almost always false economy.