If you were here in Perth (Oz) I would say look around sports stores and boat chandlers. There is a huge range of types available. Typically around 30 squid for a PFD suitable for paddle board. Same as dinghy sailors use. The Rolls Royce seems to be the Zhik but crazy expensive. Very closely conforming to your body. Here's a cheap one at 30 squid Marlin H50 PFD Buoyancy Vest Level 50, $59.95 | Whitworths Marine. Just look around and try them out. Find what suits you for price and comfort. Bear in mind that you will use it a lot when falling off initially in learning. You need something that does not inhibit your getting back on the board. ol'will
Why are Zhik so pricey ? At decathlon you can try on various types in store and no one ever bothers you with any nonsense that you might want to buy one so a great place to start out to see prices and what fits best. I have an HH version BTW and no connection to Dec but they do sell paddle boards as well