Welcome to PIA. We were in a similar position to you but we started this process a year ago. Hubby is a joiner to trade who worked his way up to project manager. Redundancy meant he had to go back on the tools. We had visited Australia on holiday and loved it. We are using an agent (Go Matilda) who have been excellant. We have filled out all the forms ourselves but they gave us pointers and guidance throughout. To be honest I doubt that we would be this far ahead without them.
We now have our case officer, we have sent away for our police checks and our medicals are booked.
It is a lot of money and ultimately you need to make that decision looking back I would still use the agent. It's costly but I always had peace of mind that they were on top of any forthcoming changes and would know what to do.
Good luck with your application,