This is a such a stupid comment. Sorry to be rude. But really, "anything that impacts the quality"? Come on! If that were a rule nobody would ever have any children.
OP, there are definite financial costs, and if 3 means you'll be on the edge of managing, probably not a good idea (4 would be that for us, so we're stopping at 3). Obvious ones are car and housing. Day to day costs are also higher (food bill is the obvious one, also clubs, activities, etc). Emotionally, I find it hard to be pulled between three of them if they're all higher needs at the same time (eg when they're all ill).
But. But. The dynamic of three is lovely, much better and easier than I expected. Older two have been massively enhanced by having a younger sibling. There's lot of joyful chaos. It's so much fun.
Hard to say without knowing more about your financial situation, but my approach would be not if it made your family financially insecure or precarious, but if you can manage with a bit less (eg we haven't had a holiday for a couple of years while still paying nursery fees) it's so worth it.
Taking the attitude of the previous poster seems to epitomise to me the old cliche of knowing the cost of everything but the value of nothing.