Manuel,
I hope you understand that you are getting into something that is going to require alot of experience. This is a pretty big task for your first job! It's almost impossible to guess-timate costs on this without a GC doing a thorough walk thru on this. Are you sure the occupants haven't poured cement or acid down the drains? They seemed pretty ticked off by the looks of the place. Is there any mold? So many questions, that only a contractor might be able to evaluate.
Now, considering that everything is pretty costmetic, I think you are still going to be around $50k. I've rehabbed a few like this, and there are ALWAYS unforeseen hiccups and repairs. You don't have steady contractors that will be discounting much to you yet, so I expect you will be paying close to full cost for contractors.
I am not familiar with bldg code requirements in your region, but where I live, rehabbing this type of property requires permits. On one of our rehabs, we had a dumpster in the driveway for demo material. An Inspector drove by and slapped a "stop order" on us. We had to pull full house permits and submit full house plans, even though we weren't changing anything in the original footprint. It cost us ALOT of time and an additional $5k in permits, drawings, etc, etc. My contractor told me "don't worry about permits.... you aren't changing the footprint (only remodeling existing)". That's the last job he got from us!
Anyway, pls do yourself a favor and gert a good qualified GC to evaluate everything for you. Yes, this might be a good learning experience, but it may also discourage you from future fix-n-flips. The challenge might be overwhelming for a newbie (Just my opinion). If you decide to move forward, I wish you the best of luck. Keep us posted :)