I would check out Film Emporium http://www.filmemporium.com. They tend to provide very reasonable-ish rates for a lot less than 30 days.
A couple of things that can change your rate:
Go for the $1M per occurrence / $1M aggregate policy. That’s usually the lowest one offered. If you’re shooting on NY State property they usually want a $2M policy but for NYC permits and almost everyone else the $1M/$1M policy is plenty
Equipment and liability are usually bundled together. But you can specify the replacement value of your gear, props, wardrobe, etc; assuming you don’t have much gear, a lower replacement value will somewhat lower your quote.
Assuming you don’t have stunts, underwater sequences, or you’re shooting a music concert (I wish I was kidding about that but it’s in a lot of the applications), that should lower the premium as well
Another option is to ask friends who have production companies with long-term policies. They can subrent insurance to you by adding you/your production on as a rider to their policy.