A possibly cheaper route would be to replace the garbage, oxidized easily brass jumpers that come with speakers to something of higher quality. Bolder Nitro's w bybee's, albeit $$$, made a signifigant differnce to my ears. There are however much cheaper options that would still be an upgrade. You can always use a short run of the SAME speaker cable you use currently to bridge as well.
Try it. Bi-Amping is nice, as you are generally able to use a much cheaper, possibly pro sound amp on the bass and a much higher quality amp on the mid/tweeter and will have a noticeable differnce in sound as well.
Good luck!