I want to buy a or multiple parking space(s) in Chicago with the
intent to then rent them out on a monthly basis as an investment
property. I tried to find any info about it, but can't find any.
Please help me by answering or providing info or articles on the
following areas:

- Parking Space Depreciation
- Parking Spaces as Investment Properties
- Success/Horror Stories
- Parking Space List serve or Auction Site
- Tax info related to Parking Spaces
- Any other info that may be relevant to parking space investments

I can tell you that the likelyhood of a parking space in Chicago 
declining in value is pretty slim. Years ago I bought two spaces for
my wife and I in the LakeView neighborhood. Since then we have moved
out but began renting the spaces to friends of friends. I have been
offered nearly twice what I paid. The trouble with this is it was dumb
luck that I ran into the spaces in the first place. I happened to rent
a place and the land lord offered me the spaces. My best guess would
be to call some bigger rental management companies. They should be
tied into who owns/sells them. From my little experience with this
it's tough to find 1-5 spaces. Sellers usually only deal with bigger
investments. Whole lots. Again, that is what I have seen in the
LakeView area (Broadway&Addison Areas) Hope this helps!

Just some quick thoughts:

1) Property values over the last many decades have increased slightly
faster than the rate of inflation (just over 3% average per year). 
There has been a recent surge in prices over the last 4 years, but if
this continues much longer it can't lead to anything but a crash in
prices.

2) Think of all the costs you'll face with parking spaces.  Will you
have to man the spaces?  Will you have to hire someone to tow
illegally parked cars?  Will you have to repair the pavement?  What
will the signs cost?  Will it cost you anything to get rentors?  Are
there property taxes for parking spaces?  What will it cost to collect
your rent?  I'm sure I missed many more, but I'm no parking rent
expert.

3) Your opportunity cost is about 11% (what you'd likely get investing
your money in the market).  Can you beat an average return of 11%
after all your expenses?  How certain are your returns (Will the
spaces ever be vacant for any amount of time?  If your rentors don't
pay, how quickly can you get rid of them and get a new rentor?)  The
taxes on your gains as a "landlord" will all be taxed.  As an investor
you can avoid taxes on the front end with an IRA or on the back end
with a ROTH IRA, would this be more advantageous to you?

Just my thoughts.  If you have a real passion for this or if you have
good confidence that you will be successful in making a better profit
than you could in an index fund for instance, then it could definately
be a good idea.  I wish you the best of luck with your investment
endeavors!