Yeah, not trying to hate, but with the limitations you put up..... It will be very hard to find a one bedroom for 700-800. Most people I know who pay that kind of rent have roommates.
Your best bet is to get lucky and find a studio or "cozy" one bedroom in Wicker Park. There are deals that can be had there. I am not sure why you are limiting yourself to the blue line, unless that is where your office is, or maybe someone recommended that to you, but there are a lot more "diamonds" in areas like the West Loop. Anything East of Ashland(1600) is a great area to be in. The green line can bring you into the loop where you can catch almost any color imaginable.
Also, you could think about UIC Village. There are a lot of safe inexpensive areas down there. Heck, if your gf will cook for me, she can have my extra bedroom for $400. DirecTV, Comcast internet, and a 2 minute bus ride to UIC.
That is now studio range instead of 1br around here.
Unfortunately for the op his options are limited if he wants to live off the blue line near the city center (mostly shitty hoods except for Wicker Park and Bucktown. Logan Square is a decent compromise and if he hunts around he might be able to find something close to his range.
Yeah it's more like that would get you a junior 1 'bedroom' or studio in LV now.
The real problem is not only 700-800, but close to the blue line. You can find 700 dollar places in Logan but you'll be walking 15-20+ min through a not-so-great area to get to the train... and at night? fuck that.
oh yeah, I forgot about Bucktown. I think OP should start considering train + bus routes, which is really no difference in cost, just time and pain.
There are plenty of express bus routes--I'm sure on the west side, as well, that are just as efficient, if not moreso, than some of the train schedules. or at least, they are the only real option depending on where you are, as the L coverage is so limited. Sadly, I envy it now.