I would advise that if you ever go to a computer show and sale, to keep a sharp eye on the vendors. Here are some things that I would strongly advise you to do.
1. Ask to see the sales receipt that you will have to sign if you buy a product from them and read the fine print at the bottom carefully.
2. If there is a statement about components and parts, ask what the definition is.
3. Question any statement about a restocking fee.
4. If they say that the restocking fee is waived or doesn't apply, ask if they will scratch it out and initial it on your copy of the receipt.
5. Ask if they will make good any defective products (either replace or refund) within the required 30 day period or if you will have to rely on the manufacters warranty.
6. Ask if you have to pay the restocking fee on defective products to get you money back.
7. Ask if they are local. (50 mile radius of show location)
8. Buy only brand names. (example: Epson, Creative Labs etc...)
If the vendors seemed to be annoyed, get defensive, or take an in you face attitude, my advise is to take you business elsewhere. I am speaking from experience. There are some vendors who believe in good business practices and if you ask the questions above, you will find them. I know that the prices seem low compared to some chain stores but if you look in your phone book yellow pages you can find a local computer store or supplier who will match or beat the show price.
If you have had any bad experiences with Computer Show Vendors, please email me as I would be interested to hear them and share my stories.