The standard distance for NRA and ISSF-sanctioned air pistol (and rifle) competition is 10 meters, and the ISSF has official targets for those. The 10M pistol target has an 11.5mm 10-ring, the other rings are 8mm and the center area through the 7 ring is printed black. As noted, you can buy those in bulk printed on good paper that punches clean holes which is probably best.
The Wikipedia article on the 10M game is quite a good starting point:
en.wikipedia.org
In the UK, 6-yard competition is also popular for smaller interior ranges. Here's a site that has both targets as PDF's for download:
Free A4 Air Pistol targets to download and print. A range of A4 printable Targets for use with Air Pistols. Including 10m & 6yd air pistols targets.
www.craftygeek.co.uk
Here is an interesting article describing how to scale the 10-meter target, and its mounting height, for different distances:
Calculate the proper target height and size depending on the distance you are training at.
www.olympicpistol.com
A typical 10M match is 60 shots, and I'd say a competitive score at the local level is maybe 500 or so? Here's another Wiki article that chronicles how the world record score has progressed over time (note that the number of shots, target sizes, and scoring methods have changed over time). It's rather humbling:
en.wikipedia.org
Tons of other printable targets out there, too - just google "printable air pistol target." Good luck!
