Dan, the strike price is what the principal amount of the bonds gets converted to in shares.
Eg if you have $1000 of convertible bonds that convert at $1 per share you hope that the share price is over $1 because you'll get 1000 shares when you convert (that will then be worth more than $1000 which is what you paid for the bonds).
I'm not sure why you think the bond holders pay anything to the company to convert the bonds.
