I think the BOLT is worth it, but not sure the bundle is worth it. I've love my BOLT but I have a Wahoo HR monitor and the garmin magnetless speed-cadence sensors. I got everything peicemeal but I also know a Garmin employee who got the sensors for me at a discount, so they ended up being like $35 instead of $50.
Any ANT+ sensor will work, but you're not going to find more than about $10-15 in savings among sensors and it's probably not worth it to go with super cheap no-name mystery sensors because they *will* fail (he said, speaking from experience).