The job fairs that I have gone to start in the late morning, I usually jumpseat out, do my thing, then go back in the evening, don't see the need to get a hotel room unless there is no way that you can get there in time. It'll save you some extra cash from what seems to be a scheme to pay to beg for a job.
A lot of the time you'll only spend a few minutes to talk to the representatives of your target company. For me, I've handed them my resume and then only to be asked "Did you complete the application online? If not then do that when you get home." $120 for a 2 minute conversation