It’s going to cost big bucks to get under the big top for the final “Greatest Show on Earth.”

Tickets have sold out for the Ringling Bros. and Barnum & Bailey Circus’ last show ever, on May 21 at the Nassau Coliseum — with scalpers asking nearly $300 for a ducat.

Ringling is folding up tents this year after a major decline in attendance.

Tickets for the Long Island show were $48.75 before the aftermarket price hike.