You can make an inexpensive drain with coarse (1" or larger) gravel (we always called it "chat") and perforated PVC septic pipe.Ah I see. I only need about 30-40 feet and likely a 6" pipe.
Put some chat in the ditch (make it 6" or so wider than the PVC pipe), then lay the PVC and cover it with the chat to ground level (or very nearly so). Be sure to point the holes more/less downward (the pipe I've used had two rows of holes approx 90 degrees apart), so the PVC will be less likely to fill up with dirt and sediment.
Just my 2¢ ...