If you have a good relationship with a local printer, or know someone who has a relationship with a local printer, I'd go with the local printer.  The quality will look much better than using Vistaprint or some place like that.  And they are more customizable. 

You want to make a good first impression on correspondence you send out to prospects or clients. Spend the money and use a quality local print shop. Make sure you have everything compliance approved prior to printing otherwise your firm will have a field day. You may also want to ask them if they are willing to pick up some of the cost… 

http://www.boxesbypandora.com/

If you have a good local printing business in your area, you should definitely go local. You will be supporting your community and you might get an account out of it. You never know.

its not the printer you use, its the quality of the paper its printed on. Use a high rag content, probably 28 lb stock. Have you logo and names embossed so they rise off the paper (embossed is not the right word but you get what I mean).