$150.00 a year is pretty standard in the industry for the first $5k of coverage for mortality, colic surgery and theft, and I'd doubt you'd find it cheaper, but you will get a few companies that charge more.
I use Plamp Keen, and they are friendly and easy to contact via email. Plamp-Keen Agency
I have no idea how much you're looking for in insurance, but anything under $20k, I believe, doesn't require a vet to examine the horse or an appraiser. You just tell them what the horse is worth or cost you and fill out a one page application - very easy. They will start the policy before getting payment and you have about 14 days to send it in.