Along these lines, consider replacing an electric dryer and/ or range with natural gas ones if this applies to you. It's very likely doing so will drop the load on your 100 service so that you can run the 240V without upgrading. You'd get shiny new appliances for less than the cost of 200 service upgrade. If none of this applies or you're running additional heavy-draw things off your box, ignore this altogether.
I see you live in Chicago. My friend's a licensed electrician and recently did my 240V with a detached garage. The only catch was I dug my own trench, no biggie. If I would've did it with no permits (in retrospect I really should've, such a goddamn sham), costs would've been a good bit under 1k. With permits and all the BS that accompanies, around 1k.
Let me know your thoughts, and if you're interested, I could probably set you up with my guy.