The Dymo does not require ink. You can print one single label or highlight a few from your database and print them for invoicing. You can also build up a database like I have done and put in different groups eg: Architechts, solicitors or whatever and print labels for a mailshot.
It took me a while to buy it because of the price, but its one of them things that will save you alot of time and you can deign your own logo onto the address label and gives your post a professional image
Highly recommended
Cheers