Here is a site set up for forum members. They offer NEBS forms (most popular mail-order forms for decades) at a significant discount to forum members.

Checks, invoices, stastements, proposals, PO's and a whole lot more. Many are QB compatible. They have both multi-part and single sheet forms and ship in just a couple of days. I've been using them for years. I also buy their business cards and small labels to stick on the bottoms of giftware I sell.

http://giftboardservices.btobsource....ser/index.jsp?