25/50 is usually state minimum coverage (states vary just advising this is the usual minimum)
I've never had less than 100/300 but I've had 250/500 and 500/500 in the past.
Personal opinion but I wouldn't recommend anything less than 100/300.
As far as costs you may look into your deductible options. $250 is fairly low. Usually, though not always, the higher the deductible the lower your costs (since you will be upfronting more $ in the case of an accident).
Rates can def. depend on where you live and the insurance company you are with plus a wide variety of other characteristics so cost-wise it's hard to compare.
Bottom line though if you have questions or concerns why not set up an appointment to go over your coverage with your insurance agent?