To make a profit in any business, you need to charge a fair price. That is, deliver good work and know the value of what you provide. Subsidising other people's businesses is not healthy.
Then you offer to do subsequent pages at your working rate. Big smile (even over the phone), big enthusiasm. Your rate and revision policy are what they are going forward, but help the client envision how amazing the end result will be!
They may try to negotiate your new rate. Give yourself a little wiggle room so that you can accommodate a negotiation if necessary. If they flat out refuse, then take it as a learning experience and spend your time finding a new client.
The only thing that you can convince a potential client of is that you won't work for less than your proposed fee. It's hard to walk away from potential work, but more volume of money losing projects doesn't make up for the fact that they are money losing. And a client promising lots of money losing work isn't worth keeping as an active client.
That's not to say never take a money losing project. Big established organizations with ample budgets often have orbital rings of larger and larger projects. The minimum overhead of working with them makes small projects in the outer orbit produce small losses. But small projects are the route to the orbits with bigger projects with obvious profits.
Your new rate reflects a reduction in their risk since they know you can do the job.