depends on if it's "local", "distant", or "long distance".
we did a local move (within the same town) and within 9 months moved with the same items "long distance" (from california to washington). with the local move all the companies looked at the sq. footage of the house and it's contents, estimated the time to pack the truck (we would pre-pack all items that needed to be in boxes), travel, and unloading-based it on an hourly fee.
with the "long distance" (same packing criteria)-it was based on weight, distance and destination (also kinda a factor was the timing of the move-if a company had regional moves schedualed we got a better 'break' b/c they would be traveling to the general vacinity of where we were moving).
we used allied-one thing that was a benefit to us was their policy that if you had any ties to military (active, retired, dependant) or government (active, retired, dependant) they would offer you the contracted rate those agencies had if it was lower than your estimate. they were also willing to lock in the mileage factor (driven by fuel costs, if fuel costs went down after contracting, the price went down but if they went up you were locked into the rate at the time of contract
).
one thing i'll suggest-call your renter's or homeowner's insurance company and find out your coverage for transported items. then you can look to what the moving company charges and decide if (1) you need additional insurance on your possessions, (2) if it's a good deal to get it through the movers, or (3) if it's a better deal to up or get a special rider through your insurance company (with us it was a better deal to get a cheap policy through the movers that would cover our deductable through our homeowners).
we used movers for the bulk of our stuff-that said...we had to transport vehicals so we rented a small u-haul trailer that we towed behind one. in that trailer we put our person items, antiques and documents that no amount of money could replace. we also put in the items we knew we needed to survive for the 3-5 day range that every moving company said they would give for actual delivery at destination (they give a deliver range of days but call the day before to let you know that delivery will occur the next day-we also packed one small t.v.-that way we could set up our direct t.v. installation for a day immediatly after we arrived such that when the rest of the t.v.'s showed up we could hook them up and confirm no damage had occured).
TIA!
To pack us, move us 900 miles, unload us and unpack a few boxes would have been over $10,000 
