There are some online antique tool dealers but they tend to ask top-of-the-market prices for their wares and you will most probably still have to restore them to some degree before you can use them. Most tool dealers won’t restore a tool because it isn’t cost effective and collectors often don’t want restored tools. EBay can be a good source, especially for folks that live in areas without a woodworking tradition and history but you run the risk of getting a bad tool. I have never bought from online used tool dealers or from EBay because I have been able to find tools locally through the years. I have bought a lot of tools at the flea markets but the type of markets that often feature old tools (folks bringing their own items) seems to be drying up. I now find most of my stuff in estate sales and you can reduce the time invested by being selective about which ones you go to.
You will always be faced with the issue of buying new, where you will probably spend lots more money and will still have to do some work on the tools, or spending much less on used older tools, having to restore them, and spend some time hunting them out. But the older tools will probably go up in value as antiques and a lot of folks get great pleasure out of doing traditional work with traditional tools. I currently have a project going where I am restoring an old collection. Part of the enjoyment in this for me finding the owners stamps, figuring out the type of work most probably done from the tools present, and getting some idea of the workman’s skill from the condition of his tools. Last week I restored a wooden fore plane that had wear marks in the plane body from the fingers of the original owner. Imagine the number of times that woodworker must have used that plane to leave indentations worn into that plane body. It is almost like shaking his hand across the years when I use the plane the same as he did and that plane has many years of useful life left in it.
I always recommend that newbies try and find someone in the area that has been into hand tool use for a number of years, They can be an invaluable resource. Don’t be impatient with the process. Finding an old tool and restoring it will teach you a lot about how that tool works and how to keep it operating at its best. The hobby is not just about making stuff. It is about the history, it is about training the hand, the eye, and the mind, and having fun in the doing.
Have you been into it enough to develop a “wanted tool list” yet and what part of the USA are you located in?