I'd estimate my 07 dodge ram 2500 is probably around 15k. Honestly, I'm not sure if there is much difference in cost between liability and full comprehensive insurance. I pay $50/month for this truck. I guess it's one of the benefits to having an older vehicle. The biggest difference is who the carrier is.
To get back to your original query, I'll tell you I'm very much in a similar situation with a 40K-mile '08 Charger R/T I bought brand new. To get a solid opinion you'll need the actual delta in the premiums with and without comp/collision. I still have full coverage on the Charger, not only because it's still in like-new condition, but also because the premium increase is only about $40 per six months (I pay $260 every six months; it would be about $220 without comp & collision)...with a $1K deductible. Not a lot for a little extra peace of mind.
To further muddy the water, though, I currently bundle my cars and homeowner's insurance through Allstate. As a result I have a little more to compare when it comes time to pay the premiums. But in any case, I shop coverage every six months and have zero loyalty to any company. Many companies would dump you in a hot minute after a claim; why people are so loyal to insurers is a mystery to me.
Just asking here, but if premiums are a concern why pay monthly? Most companies offer a nice "paid in full" discount when you pay for the entire 6 months or year up front.
Anyway, as HowAboutThis suggested, plug in all the data online and see what makes the most sense for you. And definitely shop, shop, shop. Try all the big ones (GEICO, Progressive, USAA (if applicable), etc.) and a local or two. It really doesn't take too long. All the best!