Unfortunately the IMS shows are dying. There used to be 13/yer and I think it is now down to 9 or less. For the past 20 years they have been getting smaller and smaller as well. The "big guys" are what supports them and they aren't all in good shape which is why they have shrunk. It is VERY difficult to track the value of the shows other than anecdotally. Over the years I have only been able to track a small handful of sales to the shows. To be sure there have been more but the result is questionable for all of the brands.
The company that owns the shows also does shows for most any industry you can think of. With costs being what they are and motorcycle sales falling it is just too tough to expand these shows. An average small booth ( we used to rent 4 and RENA is doing more) is about $1,500/booth. If you are Harley etc. it gets to be a big number. However that is the tip of the iceberg. You have to have a decent display $20,000 - $500,000. You have to pay people to assemble it and disassemble it which takes hours. In some cities (NY, Chicago and others) you have to pay the unions. In many cases you can't even plug in your own lights. Many houses won't let you "roll" bikes in and out. You have to pay a Union guy to do it. Mostly we just pay and then do it yourselves. No negtive comment about Unions, just laying it our there. You have to pay people to be there (in most cases if employees of the company are there), hotel rooms, airfares, food etc. The really big cost is moving the booth, motorcycles and people from city to city. For example if I wanted to move 4 bikes from show to show that alone could be as much as $20,000.
To be sure it could be done at a county fairgrounds but Advanstar would want nothing to do with it and frankly the OEM's would welcome the opportunity to not have to attend. It's one of those deals where you are noticed if you don't show up and others do. For example Triumph disappeared for several years and it didn't hurt them one bit.