Wildcard SSL for ProSites / Multisites

I bought an SSL certificate from my hosting company. Of course now when I use multisite to create a subdomain (so I can use Pro Sites) a message pops up prompting people to not go to that subdomain address because it is not verified. I see the wildcard option from Verisign / Symantec is about $2000 per year which is not viable for me being a startup. I know there are some less expensive options out there… but…

Isn’t there a way to ONLY apply the SSL cert for registration, login and purchase pages so the remainder of the time there are no issues?

Please advise!