Creating checkout process for conference registration vs. individual class registrations

HI - I am a fairly proficient IS user, but this one has me stumped.
We want to set up a checkout/shopping cart solution for people that are registering to attend a conference.
HOWEVER, I need it to be able to apply LOGIC to adjust the final price, in certain situations which cannot be driven by tags.

The user can select up to 8 classes total. If they select more than 5, they are then eligible for the “full conference rate.” Yet they can still select up to 8 classes.

Should I just separate them on the first page, into individual class purchasers vs. full conference purchasers, and take them along the appropriate path that way
OR is there anyone that has built something like this that is pretty straight forward, and available for sale (time to help me build it or send me the stuff I need, don’t care which…).

I hope I am explaining it clearly enough -
I would really appreciate your input! Thanks so much

If it was me, I’d offer the different pathways up front if saving time and expense for yourself is a priority. Another option would to add PlusThis as a 3rd party app and create a two-step process. Step 1 is to collect some details from the person ordering including their choice of either individual or full w/tags applied on the choice (that way if they abandon, you can followup with them in Infusionsoft) and then use PlusThis’s Smart Links to route them as it looks for the proper tag.