While the software itself costs money, many dealers will perform a firmware update for free or a small bench fee ($20–$50) if you purchased the radios from them. Call the dealer and ask: "Can you run the KPGD3 utility on my TK-3180 for free since I bought it here?" Often, they will say yes to retain your loyalty.
If you are a hobbyist, joining a local radio club can be a great resource. Members often share tools and expertise (within legal limits) to help peers program their gear. kenwood kpgd3 free