Parking Lots ... Parking Lots Everywhere
Parking around Chicago O'Hare Airport seems to be a highly requested service, considering the number of options that can be found on the web. The reason behind this is probably due to the lack of convenience of having to catch a train from the economy parking lots to the terminal, or to the lack of cheap (≤ 10$/day) parking spots. To be fair, convenience has a price. Therefore cheap convenient parking is probably somewhat of an oxymoron.
Parkings Including Shuttle Bus To/From the Terminal Building
Looking around the web I stumbled upon this website, which offers a detailed list of parking services neighbouring the airport. The cheapest options tend to be further away from the terminals, and offer direct-connection shuttles, running at frequencies between once every 5 or 10 minutes. The rates seem to oscillate at around 10$/day, give or take a few bucks. These include a city tax and a county tax which each add up to something around 0.50$ per day, i.e. 1$/day in total. See the figure below for a dummy 5-day (
5 * 24h) booking with this company picked at random:
For completeness sake, I just discovered SpotHero, which is a mapping tool which can be used to locate parking spots by geographical position. Using
O'Hare Airport, Chicago, IL as a search term yields the following map of results. Aside from the airport parking, the rates retrieved by SpotHero seem to be oscillate between 8$-10$/day. Most of the services offer shuttles to/from the airport.
All in all, the results of these searches show that there are plenty of parking options in and around Chicago O'Hare Airport. Indeed, owning parking lots seems to be a very profitable business in Chicago. Prices across different services might vary by a few bucks but generally speaking they are all similarly equipped: 24h access, shuttle to/from the airport, car wash service, etc.
Having said this, convenience and cheapness are somewhat subjective parameters. It will therefore be up to you to pick the option which suits you better.