Nothing to buy, just use sawdust from the table saw or a shop of a friend and scatter it around your plants lightly. If you don't have sawdust, I have used corase corn meal. Does a great job.
By gbk from south GA
Keeping Slugs Out of Your Garden
Using Sawdust in Your Garden
Uses for Sawdust
Use Beer to Prevent Slugs
DIY Sawdust Floor Sweeping Compound
Getting Rid of Tiny White Biting Bugs?
Use Sawdust as Cheap Wood Filler
Use Coffee Grounds to Deter Slugs
Tiny Black Bugs in the Kitchen