Right now, its $217pp, so $21,700 up front plus about $300 closing costs. so call it £22k.Do you have a rough figure? And isn’t there a yearly payment too?
Annual dues at Riviera are $8.50pp, so $850 this year. Worth noting that Riviera is a newer resort, so the Dues won't increase much for now (was only a 0.8% increase into 2023). As the resorts get older and come up to their hard refurbishment (where they strip it back to the dry wall and start again), the increase is more, this year Bay Lake Tower, Animal Kingdom and Boulder Ridge all had 4-5% increases. I ignore the dues increases for Hilton Head, Aulani and Vero as you go into those knowing they'll be a lot higher as they are on the coast an susceptible to Salt Water and Hurricane damage.
IMO, they are crazy to have bought 100 points direct, around the time they bought you could buy 100 Saratoga points for half that on the resale market, and it has lower dues too despite having just had a full refurb.