Insurance policies and rates, even with the same company, vary state to state. I used to insure my dirt bikes through Progressive, but dropped them because they were passing on a $100 surcharge due to an interpretation of a Michigan-specific insurance law. Otherwise their rates were good.
I checked with State Farm, and although they did NOT assess the same surcharge, they required collision coverage, so the resulting premium was about the same as Progressive.
I'm now with Bike-Line (Markel). They do not assess the special Michigan surcharge, and do not require collision coverage. Here's my coverage:
Liability: 100/300/50K (you could go less if you don't own home)
Comprehensive (fire, theft). $250 deductible
Accessory / Aftermarket Parts Coverage: $1,000
Premium: $117 per year
Bike: '04 KTM 200exc
Unfortunately Bike-Line does not insure kid's bikes, i.e. generally anything under 150cc. Their web site does list some smaller bikes, but if you call direct and try to get coverage on them, you'll be denied.
FWIW, I don't think you need collision coverage on a dirt bike.
Also, if you have loan on the bike, some lien holders require full coverage, which can be an unnecessary expense.