Using a plotting service can be a good alternative to purchasing your own plotter. Or you might consider using a low-cost plotter for check plots and then sending the files to a service bureau for your final product. Most reprographic services, such as blueprinters, offer plotting in conjunction with their other services. Quite often you can send files over a high-speed connection, eliminating the need for using courier services or regular mail.
If you foresee the need for service bureaus, consider establishing a relationship with one or two service bureaus fairly early. Send them some sample plot files to make sure that they will produce the results you want. One of the greatest difficulties is miscommunication between what you want and what the service provides in the way of plotter output.
You might be able to use the PC3 and other plotter setting files as part of your relationship with a service bureau. Plot configuration files and plot style table files can help communicate exactly what you're expecting.