Which plugin to use for guided tours? Events or Appointments?

OK, I'm hoping someone can help me figure this out.

I'm building a site for a client who does guided walking tours and wants to sell tour "tickets" through his site.

Because he doesn't want to do a tour without making at least $X, he wants to set the minimum price for a couple at $100 and then sell additional tickets at $20 each, up to 10. So if it's a couple with two kids, they'll pay $140, and then if another couple wants to sign up for the same tour, they'll pay $40.

I don't necessarily think this makes sense from a business standpoint, but this is what he wants.

So basically, I'm trying to figure out how to set this up in a plugin. I've tried fooling around with Events and with Appointments+/Marketpress integration, but I can't seem to figure out whether it's possible to:

a) have someone be able to purchase multiple tickets at different prices
b) have the plugin force-sell the 2 $50 tickets first.

Can someone tell me whether it's possible and help me configure these options? Thanks!