If using shared hosting you're pretty much dependent on them anyway (unless it's Apache hosting and you can put your certificate stuff in .htaccess? Not tried).
If cost is that much of an issue, and you can't pass it on through what you're charging users, find a host that's cheaper on SSL? But you want reliability, so might have to bite the bullet. If it's education, you can probably get it cheaper but depends if you can send the hosting outfit a pre-purchased certificate package.
