5 is actually not low...that would be a new cert every weekday! If you need to test scripts, etc they always have the staging server that you can test against that has low/no limits AFAIK:
Keep in mind (from my OP), this count determined by the number of certs upon which a given domain appears, NOT the number of times it appears on a cert. So,you can have successful issuance of a cert that looks like this
domainA.com
www.domainA.com
a.domain.com
b.domain.com
.
.
.
z.domain.com
and then a second cert issuance with
and that only counts as 2/5 of the limit being discussed, even though you have now 29 hostnames covered with those two certs. Does that make more sense?