Given that you're either already using an illustration package or have access to someone who does, I'd take the DIY route. In OpenOffice Draw, the basic steps would be:

• Use Tools / Options / OpenOffice Draw / General to set units to mm, then set up a page of the proper size with Format / Page

• Create a circle of whatever visible size you want (e.g., 2mm), set its color and fill properties to light grey or something else subtle

• Right-click the circle and select Position and Size to size that circle down to something much smaller (fraction of 1mm), and place it at 5mm from the top and left edges

• Duplicate that circle 36 times (should take a total of 37 dots to span the roughly 180mm, and you've already got the first one done), with a horizontal spacing of 5mm and a vertical spacing of 0mm (Edit / Duplicate menu)

• Select that row of circles, and duplicate them 48 times with a horizontal spacing of 0mm and a vertical spacing of 5mm

• File / Export as PDF

• Carry the PDF to your print shop, or print it yourself. 67lb paper runs under $9 for 250 sheets, and you may find better options.

And you can check the official DIY Planner Widget Kit if you really want them to look nice.