Just to build on @Ron_Case’s answer: HW3 to 5 are limited to firmware 6.3.4, and the throughput is lower: HW1-4: 170Mbps, HW5: 200 Mbps and HW6: 1Gbps.
HW5 and 6 both support up to 30 SpeedFusion partners.
There are quite a few used B380s for sale on eBay at any one point in time. HW5s seem to run about $600 (give or take). But be careful, the sellers can be quite vague about which hardware revision they’re selling. For an easy check you may reference B380 HW revisions - looks.
Cheers,
Z