I have checked out a couple of taxi/shuttle services and I am coming up with prices in the order of Euros 140 to Euro 150.
I spoke to the Praia del Rey resort themselves and they have a service available via their concierge. Price per taxi not per person will be Euro 100.00 from Lisbon Airport to the resort during weekdays. After Hours and week-ends this rises to Euro 150.00
These taxis can be booked by emailing the concierge at:
concierge@marriott-pdr.com.pt
or calling
+351 262905100