Glad to see others chimed in here. There are a bunch of good folks here that love to encourage and see you succeed. They motivated me into riding and changing my life. I hope that the stars will align for you to be able to get your surgery and not have to worry about loosing your job. I will put a request in to the "upper management" tonight before I sleep and see if that helps any. I have been watching Craigslist as I said I would and here are a couple bikes as examples of the price and type of bike that might fit your requirements when the time comes. These were both listed on the same day so you can see that finding a decent used bike when you are ready shouldn't be an issue. I have seen 12-18 that would fit the bill in the past week here in Columbus, so finding a bike should be no worries when you are ready.

These two are mountain bikes, they would obviously only be an option if they were the right size for you. With a mountain bike or even hybred, many here (myself included), switched the knobby tires out for a smoother tread making the bike ride better on pavement and is an inexpensive "upgrade".

http://akroncanton.craigslist.org/bik/1387271359.html

http://akroncanton.craigslist.org/bik/1387473034.html