Why is that strange to you, Nitroflare is a dead hoster.
One price advertised on the site, another, much higher price when paying. Would you buy such a premium? They don't even have an option for credit card purchases, everything goes through resellers, and that's why the prices are much higher.
From their website: Popular (90 days) + 30 DAYS FOR FREE! = Price: $35.00, when you get to the last step:
PackagePopular:
Duration120 Days
Amount$35.00 (approx: €32.49)
Our Fees$10.50 (approx: €9.75)
Reseller Fees$9.10 (approx: €8.45)
Total$54.60 (approx: €50.69)
That's almost a 60% higher price, who's crazy to pay that much?