Are expensive translation companies better?
Absolutely not. For example, some translation companies who aim to serving large enterprises hire a large team of project manager, account manager, and sales people so their translation rates are at the higher end. If you use their services, they might pay your money to the sales people more than the translators. You can image their quality would not be good. Unless the name of your company is Microsoft or IBM, you can safely pass those who quote far above the average.