Nowadays printing 1000 copies of a flier is as easy as printing one. Desktop Publishing brought document creation and printing to our desktops only a couple of decades ago, a lifetime ago for to some people but a drop in the bucket compared to the history of printing and publishing. Today, volume printing can be as simple as typing in a number in a print dialog box, but beware it is not as cheap as you might think.
For a 1000 copy 8½ X 11 flier double sided done on your friendly ink-jet printer could run close to $700 with paper and ink.
Taken to your local professional printer you would get much better quality, a better paper look and feel, a less fragile surface and a cost that would save you at least several hundred dollars and a lot of time. If it requires folding for mailing it would come back from your printer folded.
Another big plus is you receive the expertise from the staff of your printer with each and every order.