Please do not post the same thing multiple times. The board software automatically flags certain posts as needing moderator attention. This happens the most often for new users. I'm pretty sure this is made clear at the time you attempt to post. Posting the same thing over and over again just makes that many more posts the moderators have to weed through later. This makes us sad. Don't make us sad. If your post/thread doesn't appear, just wait a while. Don't post it again. If it hasn't shown up by the next day, then you can try again. I normally go through posts in the mornings, and try to check a few times throughout the day, but I'm not here 24/7. There will typically be a significant delay before posts are approved. Just be patient.
I also recommend against doing anything that depends upon their sales. If you want to agree to a delayed amount for the final payment or two, that's one thing. But it should be "no later than 6 months, $500 due, by 12 months, $500 more due", etc.
If you are going to do fixed-fee work, then make sure the deliverable is carefully defined and documented up front. Nothing like being half way done only to have them start adding features. I would probably define an hourly rate for any work that strays from the original specification. But then I only do hourly work, so I'm biased that direction.
If they can only afford $5500, then I don't understand how options B and C are available. Sounds to me like they can afford $6500. So at this point, it is merely negotiation, and that's fine. Your $7500 is just a guess. The longer-term options are just hassle, and not really that much money. Get something up front, and then regular payments and milestones, and something upon delivery, then be done with it.
And don't agree to anything that is contingent upon App Store approval. Agree to deliver legal code, but you don't want to be responsible for Apple's approval whims. That is your client's risk, not yours.