You need to look at the terms of your contract with the strata manager. It could be that you are allowed one agm and, say, one egm per year. Or maybe they were just being generous with the first one.
My immediate thought is that $350 doesn’t sound excessive to me, given that an agenda has to be prepared and distibuted, and (perhaps) a location organised. Then there’s the strata manager’s time in attending the EGM.
Of course, if all those other charges were to be put on top of the SM’s fee, that might be a different matter. Have a look at the contract and see what it says.
In NSW, there is also time and costs involved in registering the approved by-law with the Registrar-General, plus fees. This must be done within 6 months. I’d be asking is the registration of the by-law included in the fee or is that on top.
Also, do specific owners benefit from the new carports. If so, all costs should be shared by them rather than the OC.