I'd get to the quote/job, do up the quote/workorder, they would add or subtract something, etc etc. I got tired of passing a "scribbled-on/crossed out/hard to follow/arrows pointing to the total" workorder to my clients. Then have to come home and enter everything into Mistral. So I bought a laptop and porty printer.
I also got a laptop so I could do inhome presentations during a quote. More influence from JP.
I just replaced everything, bought a $700 laptop at Christmas (my first one was $2400!! 4 yrs ago) and the HP Officejet 470 portable printer in July-$450 (the first one 4yrs ago cost me $634). Everything has a battery so no power issues. I carry that in a backpack so it looks less conspicuous in my truck, and its my office away from home. When I do a quote, or when I'm there to do the work, I enter everything into Mistral, and print it out right there. Nice clean professional work order. Wow's them all the time.
The beauty of it is, when they pass me a check right then, I enter paid, and ALL my paper work for that job is done, right there! I have a filing cabinet drawer filled with old invoices from 94-2003. I bought Mistral in Jun2000, I bought the laptop 5 yrs ago and haven't added one sheet of paper for filing since. I use an offsite email account to store my backup files.