I will chime in with my .02 and experience. Quotes are negotiable, both from brokers and carriers themselves.
Our family has used brokers, carriers, enclosed and open haulers of all types moving cars over the past year. You get what you pay for largely and a dedicated carrier will cost more but save you headaches and time. Depends how flexible you are on pickup/drop-off windows and if there is a timeline. For short distances my experiences have been nearly identical, at a longer distance I highly recommend a carrier for sanity sake. There are seasonal hikes in pricing as well, beware.