We have 2 bouncy castles - an obstacle course style one and a small one for younger children. I haven't been on the PTA for a few years so don't know the cost but it was a flat amount; children are charged to go on and it's manned by PTA and/or staff.
We have a mufti day in advance where children can wear their own clothes to school in return for bringing something for the fete eg unwanted toys or books for the toy stall and book stall, a bottle for the bottle stall or something for the tombola (we have an adult tombola and a children's tombola).
Stalls include:
Tombola
Lucky dip
Hook a duck
Books
Toys
Bottles
Spin the wheel
Sweets
Candyfloss
Strawberries and ice-cream
Gunge tank
Coconut shy
Smashing crocker
Raffle
Name the teddy
Guess the number of sweets in a jar
Crazy sand
Face painting
Teas, coffees and cakes are inside, in the Hall
Bar and barbecue are outside
We use PE benches to create an arena in the middle of the field and have a timetable with little displace from local dance, gymnastics and karate clubs - they do it for free because it's good advertising for them.
We ask local shops and businesses for raffle prizes and sponsorship. They get name checked in the programme.
Advertise the date in school newsletters well in advance and put out repeated calls for volunteer parents and staff - PTA members aren't enough.
Have a spreadsheet of volunteer roles and how many are needed for each role. Include all the stalls but also the gate, first aiders, money counters, setting up and clearing up at the end of the day.
Make it as easy as possible to sign up eg with an online form.
We give each stall holder a packet with a float, a voucher for a drink and a feedback form (what worked and suggestions of things to make it work better next year) and a pen.
Try to have a few PTA committee members who aren't assigned to a stall and can float - collect money from stall holders, give more coins if they are running low, get them a drink if they haven't been able to leave the stall etc. Walkie Talkies are handy. Hi Viz jackets or PTA tshirts will let volunteers who don't know who is on the committee, know who to speak to if they have a question/problem.
A map or plan (plenty of photocopies) will help volunteers when setting up.
Think about what you're going to do with the money at the end of the day eg ask if the school has a safe where you could leave it.
Lots of people don't use cash any more so you will have some people going to the cashpoint just before they go to the fete and trying to pay with £10 or £20 notes. Make sure you have plenty of change in the floats and if you are able to offer cashless payment, a lot of people will appreciate that.