At the lower cost end of the market is the O’Neil Hammer or Tiki shorties. Around £70-80 ish.
Both my boys have had both over the years. Most important is the fit. If it doesn’t fit you well it’s rather pointless. But then a shorty has its compromises, it adds a bit of protection for your core but if it’s windy or cold then you’ll lose lots of heat from your arms and legs.
If it’s purely for summer use then shorties are fine, if it’s spring and autumn then it’s full 3/2mm suit territory, autumn is warmer than spring by a long way.
Stock will be the biggest issue ATM, basically there’s sod all in stock.