Infertility

So we don't know for sure but we believe my husband is infertile, he has had sex with his ex's and none of them ended up pregnant and they weren't on any BC. Well we have been trying over a year now and just cannot get pregnant. I have a 5 yr old son from a previous marriage, could I be infertile now even though I already had a baby? Or is it him? We don't exactly have the funds for a spterm analysis atm and was wondering if anyone has tried anything cheapish to get pregnant with an infertile man and actually succeeded?