I am the second of 12 kids. Ten biological, and two adopted. My parents didn't have 12 kids on accident, and most of us are spaced at least two years apart. (the adopted ones are both exactly 5 months older than my biological siblings, making currently one set of 12-y/o and one set of 9 y/o) some of us are 3-4 years apart.
I can honestly say that... overall, i'm *incredibly* glad that I had/have so many younger siblings. I always used to say that "I know more about babies and little kids than most mothers of 3 in the U.S" ... just because I had so much experience with the little ones.
I remember once, when my older sister was a teenager (maybe 15) she told me, :"i'm not gonna have more than two!!" ,,,now that she has two (one special needs), she's seriously thinking about having tree or four more, as soon as she has her annulment finalized and can marry her fiancee.
I have alway known that i want a handful of kids-- between 4 and 6. I want a good-sized family, but i also want some time for me and my hubby. My mom and dad always had time for each other, but only because my older sister and I were there to babysit. (Which we liked... it was the only time besides christmas, easter, and our birthday that we got any money.)
One thing I have to say, though, is that my parents absolutely would not have had so many kids if my dad didn't stay home (for going on 21 years now!) to take care of us.
my parents work really hard with all of us, and we did wear a lot of second-hand and hand-me-downs, but i think we were all the better off for it. we spent some years in private school, when they could afford it, and others in public school, when they couldn't... I'm glad for the experience of both, but I would have much preferred homeschooling, so that's what dd will get.
honestly, my dd is right now wearing a bunch of hand-me downs from myself, my younger sisters, and my neice. My hubby and i didn't buy but maybe three outfits for her, and her cloth diapers new... and i would say the most we spent on her was maybe 700 dollars (and not all at once: a car seat, a stroller, a moby-wrap, and a bouncy-seat plus some toys). we certainly aren't very stretched, in that regard, and i'm sure that will continue for our next ones...
i think it all depends on parenting style and how much you feel the need to spend money on your kids. I really think that a lot of people in the modern world tend to (not all) equate parental love with parental money-spending, and assume that if you aren't extremely well off, you shouldn't have more than a few kids. i don't think that follows for all, but i think it's very common, esp around christmas time. for things like travel and such, i don't really know-- dh and i think we want to go places, but not sure just how yet... my family did a lot of road trips, which are fun, and it doesn't take much other than the vehicle you've already got. Especially if you camp.
Anhow, I'm just saying it's very dependent on what kind of person you are and how you parent. I honestly think you'll know, if you listen to your heart, when is the right time to stop having kids.
I can't help but remember: If God brings you to it, he will bring you through it! so... Honestly, I think it's impossible to really have too many kids... God won't let it happen. That's my philosophy, anyhow.