Haven't stayed there, but this Doubletree is listed in the back of Universal Orlando, The Ultimate Guide by Kelly Monaghan as the closest to the parks.
http://doubletree.hilton.com/en/dt/hotels/video_tour.jhtml?ctyhocn=MCOUNDT
It looks nice to me. The others in order of distance from City Walk are
Holiday Inn, South Kirkman Rd
Amerisuites, Caravan Ct
Days Inn, Caravan Ct
Come Back Inn, Major Blvd
Comfort Suites, Major Blvd
Red Roof Inn, Major Blvd
Suburban & Extended Stay, Major Blvd
StudioPLUS, Vineland RD
Sleep Inn & Suites, Major Blvd
Fairfield Inn & Suites, Vineland RD
Best Western Universal Inn, Vineland RD
You could also maybe rent a villa and rent a car for the same or just a little more. We're staying here for $925
http://www.katiesvilla.com/
You could probably find something smaller for less.
If you haven't already, I'd ask on the Orlando Board too.
Good Luck!