I have found many on craigslist but not the right one yet. The problem has been people don't really know what they have so I can't figure out what I need to get it to fit my car or they want too much.
The mentioned fit kits can be ordered online. You just enter the make/model/year of your car, and it'll tell you what you need.
Having never had one I don't have a preference for bike racks. The kind I can leave both wheels sounds nice but I don't think taking off the front wheel would be a big deal.
That's where I'd say you ought to go test some. For the "taking the front wheel off" approach, the Yakima system I'm familiar with has (had?) a little fiddly wheel to adjust the spacing of the fork clamp, while the Thule just used a regular quick release skewer, much like the one used to hold the wheel on the bike. Theoretically, the Yakima thing was supposed to be set-and-forget, but I never really cared for it.
How worried about bike theft from the rack are you guys. Is it safe enough to stop and leave the car out of your site.
Depends on the area you live and travel in. Personally, I worry -- I can't afford to replace a multi-thousand dollar bike or two. Both Yakima and Thule have locking mechanisms that lock the bike to the rack. I'd recommend using them, along with a long Kryptonite cable threaded through the frame and wheels. As with all locks, they're more to convince someone to pick an easier target, than they are to stop someone determined from stealing your stuff.
I will try REI and check them out.
Also try Rack Attack, if there's one locally.
I went to a local bike shop and they just had to order everything so that wasn't much help.
Better for you, that way -- you'd have payed too much.