i am going to replace my flexible vent pipe on my electric clothes dryer with 4" galvenized steel. i was thinking about putting a cleanout tee in the middle of the pipe. good or bad idea?

Thanks all, for looking at my question. First, I'm in Seattle, WA, and my question relates to a plumbing bill I received, after firing the company for continually increasing their price for the work to be performed. Background: I'm having plumbing work done at my house by a local company the cost is skyrocketing out of control. What started as a $500 service call has become $19,000 of main sewer line work, and this isn't even all the work needed. Over New Year's day (Friday) and Saturday they spent time working, giving me updated costs along the way. Each time the price would go up they'd go over what additional work was needed, and I'd sign a contract for that price (they didn't explain this was a contract at the time, I thought I was signing an estimate). The last 'contract' I signed was for $19,000 and change. On Sunday I called a couple other places and found out I was being gouged, for lack of a better word. I fired plumbers but I owe them something for the 2 days they spent on site. I just got a call from the supervisor and the bill for the 2 days is what I believe to be obscene. Close to $10,000 for 2 days of digging, and equipment rental. According to the other plumber I talked to (who would be finishing their work) he values the work they did at about $2500. Among other things, there is $180/hr * 40+ hours of plumber time, and backhoe rental etc... I think these rates are ridiculous, but I don't know what other options I have but to pay it, or have them complete the job since they're already half way into the cost anyway. What recourse do I have in refuting these amounts? Do I have to accept these amounts or do I have any legal ground in saying the work is only worth, say $4000. Thanks everyone. Andrew