Looks like there is no minimum spend requirement.
Book your next flight online at Flight Centre between 14 - 21 October 2015 and pay with PayPal to receive a $50 Flight Centre e-Gift Card to use towards your next in-store booking^! Flight Centre gift cards can be used towards any aspect of your holiday, including flights, accommodation, tours, car hire, cruises, travel insurance and more. Once you receive your e-Gift Card, you'll have a full 12 months to redeem it in-store at over 750 locations throughout Australia.
^Enjoy an AUD$50 e-Gift Card when you pay with PayPal online at flightcentre.com.au (Offer). The Offer applies to online purchases paid with PayPal, made at flightcentre.com.au from 12:00 AM AEDT on 14 October 15 to 11:59PM on 21 October 15 (Offer Period). Limit of one redemption of the Offer per booking, per PayPal account holder. Offer can only be used to secure a booking during the Offer period. Offer is non-refundable, non-exchangeable, non-transferable, non-replaceable and non-redeemable for cash, credit or foreign exchange including travellers cheques. If you qualify for the Offer, the AUD $50 e-gift card will be sent to you by email by 13 November 2015 to the primary email address linked to the PayPal account used to complete the transaction for the Offer and will be valid until 13 November 2016. Full terms and conditions for the use of Flight Centre gift cards can be found at flightcentre.com.au/giftcards.
Is travel insurance still valid if pay with Paypal?