Buying a caravan is a lifestyle choice, not an investment. Just like when you buy a car. You know it’s going to lose money and depreciate over time, but you get the enjoyment of it over the time you have it.
The pluses are you can buy a caravan in places where you generally couldn’t afford to buy a house - think in the dunes in Cornwall etc. It’s your bolthole in your happy place.
Site fees generally reflect the facilities available on park. So the bigger ones with swimming pools, activities and entertainment will invariably be more expensive than a smaller quiet site with no facilities. Do you actually need all the facilities or is it just the location that’s important.
For people moaning about site fees, £4,000 a year for a six berth caravan, equates to £55 per person per month. Cheaper than a lot of gym memberships. Plus it includes things like security, grass mowing, landscaping, upgrades to facilities, not to mention basically what is a “storage fee” for having your caravan on their land etc. Park owners don’t come asking you for more money to build a new restaurant or swimming pool etc.
Many parks have a requirement to upgrade your caravan after a number of years. Can be a pain, but it ensures the park remains looking up to date and well maintained.
I would also ensure it was no longer than an about an hour drive to get there. You want to finish work on a Friday and just pop there, not have to face a gruelling journey.
The let really is to find a park location and facilities that fit your needs. You will begrudge paying high site fees on a park with flashy facilities if you’re not going to use them.