I'm in this search right now also. As mentioned, be careful about the tanks you buy. I already have a relationship with my LWS so I have called a couple times while looking at used bottles to get info.
I may be off on some of this, but I've nearly decided it's better for guys like you and me to buy a first set new. First, when I've tested used torches, I can't really know for sure whether they're not working well because they're not working well, or because of operator error. Also, some sets have the flashback arrestors built into the torch handle, some will be separate, and some used sets won't have them at all. I'm not confident I can tell the difference. A new set will have them built into the handle. Also, the seller may or may not have a full set-up, so you may not be able to test everything. I damn near bought a beautiful set of older Victor gauges, all polished up and pretty, when the seller finally decided to fill me in that they needed rebuilt. At $65 per gauge to get rebuilt it killed the value, I was lucky he told me before money changed hands.
Also, torches are a pretty high demand item, so used prices aren't that much better than new. If you don't currently have a relationship with your LWS, that purchase is a good way to introduce yourself. Tell them what you want to do and let them help you choose.
The other thing I'd mention, don't get one of those port-a-torch setups in the little carrier that come with tanks. The cutting capacity is limited, and you'll very quickly be frustrated by the size of the tanks. The product description of those sets gives a large cut capacity "with optional tips", but then you find out that you can't use larger tips with the small tanks without exceeding acetylene withdraw rate safety rules.
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