For a project of your type, it's good to know you're willing to do a lot of the work yourself. HOWEVER, there are way, WAY too many 'concerns' here to advise you over the WEB. No, I don't have any links, and no, I don't think there are any step-by-step 'directions' on how to build a basement under a house. Again, there are too many variables here.
Now, what you COULD do (since you're willing to do as much work as necessary to save some $$$) is hire a professional Architect, with an expertise in Structural Engineering. Let him/her assess your home and see what would be involved in doing what you're doing. In my opinion, this would be $$$ well spent. And as you pointed out, the home was built W/O a basment in mind, so there's a lot to consider here, structurally speaking.
The only way I see it is that it will cost you some $$$ to save some $$$. Professional, on-site advice is what you need. As far as being 'worth it', you'll need to consider the neighborhood along w/its similiar houses. If there are homes w/basements in them that would be similiar to yours when it's finished, find out what they're selling for. Find out what your home is worth now. If all things are equal between the 2 homes, then the answer should be obvious. If those homes are getting $125,000 and your home would get $100,000 W/O a basement, then consider if spending $50,000 for a basment is worth it. That would mean that your home would have to sell for $150,000 just to RECOVER the cost!
Good luck w/your project. I'll be 'watching' your post here to see what others may say. My best to ya and hope this helps.