A word of caution. I bought identical ATV tank saddlebags from Princess Auto for my DR200SE. The price was right (I think I paid $15) and they fit the DR's tank just fine. However, the bags are kept on the tank solely by gravity. The first (and last) time I used them I found that above 80 km/h (50 mph) they constantly flapped around in the wind (even with the weight of a full water bottle in one side and some food in the other). I had to keep my knees pressed against the bags to hold them down, which made for a very uncomfortable riding position.
The tank saddlebags are advertised for ATVs and probably are fine in that application. However, for use on a motorcycle some way of securing the bags to the gas tank is needed. If you've got a steel gas tank one option would be to sew magnets into the bags. Another possibility would be to sew on a strap so the bags can be hooked onto the edge of the gas tank.
Bottom line: I don't recommend these bags for motorcycle use. If you can afford them, tank panniers from Aerostich (http://www.aerostich.com/aerostich-tank-panniers.html
) or Wolfman (http://www.wolfmanluggage.com/Tank/tank_panniers.html
) look like much better choices.