@pindac has the best advice - NEVER risk your health for a hobby. Or anything else. Your back is FAR to precious to gamble with. And 100 lbs is plenty big enough to destroy your back if you trip, unless you’re built like a fullback.
I’ve never regretted a Bryston purchase. I’ve used 3B SST, 4B SST and 9B SST for planars and for ESL’s and to power an isobaric sub. My wife just ordered me a pair of 7B-SST3 (40 lbs) for the bass end. I’ve got stairs, so I lined up help - no question. Once more or less in place, you can slide a unit or lever it, but don’t try to lift it with a bad back. Please.