I understand that the US economy is bad at the moment but I won't even turn the plotter on for less than $60. Get me on a "bad day" or good week when I don't need it and it's $100.
If we take absolutes and you are doing the right thing (choosing good fonts, cast vinyl etc), chances are it will take no less than 1 hour.
1) Discuss with customer
2) Design (choose fonts)
3) Turn plotter on selct vinyl, load vinyl, cut, weed, mask.
4) Use quality chemicals to clean window
5) Mix small batch of "hot" app fluid (being glass don't want the client here all day waiting for app fluid to dry)
6) Issue invoice
7) Clean up utensils and restock vinyl
Take materials out - probably costs $15. Add into that electricity, chemicals, blah blah blah and you are probably making $15 for the hour.
Unless you are quick.... not a good hourly rate to be successful and put some $$$ away for when you need to replace that $1000 piece of equipment.
To put it in context, you would have to do 66 vehicle windows to cover the $1000.
Food for thought.
Cheers - G