I'm pretty sure if you overstay too many days that you'll have trouble the next time you want to come to Thailand so I would hunt hard for a better solution
I think if you can from the beginning handle it yourself then all the paperwork for your future visits will be easy and already in your hands if you start with an agent you'll never be able to go on your own and you'll be shelling out big bucks constantly
Bummer some people got it for free and others didn't. But either way it goes to this country in some way. And aren't we all happy/ grateful to be here?