Shop around as prices seem to vary quite a bit. Those quotes sound hi to me.
I would think around $3000 - $4000 for 1/2 million liability on your truck and 1 million business liability, based on what I pay. And a lot of my customers require that amount or more.
And be aware of any restrictions on coverage, few companies will quote an unlimited policy. Many won't insure certain welding activities and if you don't look close you can miss what is excluded.
Lots of guys are happily working away with insurance coverage. It just is a cost of doing business, and has to be included in the rate.
JTMcC.