Generally ISPs will only let you announce the same prefixes to multiple upstream ISP if you have PI address space. If you have PA address space you are probably out of luck. An ISP won't accept your prefixes if they are PA space from another ISP. At any rate you can can still use floating static routes and use a GSLB provider like Dyn to get your incoming redundancy and still not need to run BGP. In fact if you have PA address space this is your only option.