Go torchs definitely have a warranty. Make sure to check to see if your part is covered.
Compared to most machines, your replacement costs for parts are really not as bad as other what I have experienced with what other companies charge.
Do you indeed want a cheap Chinese replacement motor? For something like this that is American made, you'll most likely have a really ruff time making this happen, unless your the type of person who enjoys speeding an ungodly amount of time trying to make something like this work (there usually a lot more to it, when you start Frankensteining ANY machine). You'll soon realize that the replacement part cost is actually extraordinarily cheap and it prevents a huge disaster and headache (even if you know what your are doing, you'd have to be pretty ambitious to waste that kind of time on something like this). I look at the same part list as you do, since it is pretty much the same machine (hardware wise) that I use extensive (I admit that I am probably more of a 'heap' than my plasamcam will ever be).. The only difference is that I find the some of the software upgrades are extremely useful and definitely worth the investment for what I do.
Fundamentally, there is no difference in a Go Torch and my really wonderful plasmacam. Even at its most basic level, if you know what you are doing, you can get a lot of work out your basic go torch. The go torch can be customized into a really great machine, just like my DHC2. Granted the go torch machine is inexpensive probably for a reason and primarily appeals those with budget constraints, but definitely can be made sweeter by upgrading to some of the more advanced software thru plasamacam.
In most cases any machine is usually limited by ineptness of its user. This definitely applies to me. When stuff breaks down, I get frustrated easily. That why I tend get my machine everything that it needs from the correct place from the get-go, so I can let it do its job and stay out of its way. Every time I start to thing about skimping on things that I know I shouldn't skimp on, I remind myself what my grand dad use to tell us kids: "what is cheap, usually ends up being expensive", "work smarter not harder" and my personal favorite: "never let your friend borrow your car or your wife".
Good Luck,
JAG