This reminds me of Red Robin. If you don't know Red Robin, they are mainly on the west coast, but have moved in to other markets in the east. They have the best burgers around, I mean the best. They are also known for their bottomless steak fries.
They sell an onion ring appetizer for 6.99 or 7.99, you get a tower of thirteen wonderful onion rings with BBQ ranch and ranch sauces on the side for dipping.

. Instead of forking out all of those dollars for the appetizer we sub onion rings for our steak fries for an extra 99 cents each. Even ask for the side sauces too. You get five rings if you substitute, then you ask for a refill of fries after you have chowed down on some rings. The servers are happy to provide the fries refill. So you get ten onion rings for $1.98 and then the fries too. The best of both worlds, just have to wait for your burger to arrive to enjoy the fries.
Doesn't sound like the SciFi is as good of a deal if they up-charge though. Psst, don't tell anyone what I just mentioned about Red Robin, it is a Dis secret.