Yacht holiday is not so exclusive or expensive as one might think. There are independent companies that are keeping prices competitive.
For example https://seafarersailing.co.uk is offering one week trip from £849 pp for two people sharing a cabin or £595 single supplement.
They are sailing Ionian Sea exploring Greek islands.
“Our comfortable and well appoimted yachts are ideal for your Ionian sailing adventure, with 4 double cabins, all with en-suite facilities. A maximum of eight guests are on board, together with an experienced, professional crew to look after you. Breakfast and a light lunch is included, to be enjoyed ‘al fresco’ whilst anchored in an idyllic bay. Enjoy a refreshing swim before or after lunch, it’s up to you to decide.”