I agree with the others.
So many people go out and by workbooks and resources at the beginning (including us), which then sit unused on the shelf.
We buy from car boot sales/charity shops/Ebay/Amazon new and second hand.
Travel costs are our biggest expense too.
We got a family rail card and that cut costs a lot (especially as another home educator pointed out a deal and we got it for £10 for the year)
We drive a much older car now, than we used to.
I buy them for about £300-£400, drive them for a year or two and if they cost too much to repair (not dh's forte!) I scrap it and get another!
We only go on home ed camping trips (very good value, none profit making and LOADS of fun) or we take Sun newspaper £9.50 holidays, or sign up for Travelodge newsletters and get family rooms from £9 a night for up to four people.
We use Megabus a lot-book in advance and go to Birmingham-London from £1 each way.
The children's desire and demands for designer labels disappeared overnight, so we cut on the cost of clothes/uniforms and expensive trainers immediately.
As musicposy said, gone are all the demands for money from school-and the requests to supply things for fundraising etc.
We do activities of all sorts with our local HE group and get them at educational group prices. I could not believe the price of ice skating in bowling in holiday time! It was something like four ties the price we paid!
Our group got funding for their dram productions, and that covered the cos of the dram teacher, the props and costumes etc.
The children play rugby and other team games for no cost, other than the share of the hire of the room with a playing field attached. (and travel of course)
We also organise educational workshops between us and get educational rates. We too make good use of free exhibitions at museums and art galleries.
We even managed to get two kayaks to share with the group off Freecycle (another great place for other resources sometimes as well as things like mountain bikes etc). Our group now have half a dozen (battered but working kayaks) a double canoe and a Canadian canoe between us, that we use on a local groups holiday next to the River Wye in Monmouth.
We also are big fans of Scrapstores
The children all knew we are on a limited budget as I too gave up a carer to do this. They know they have to prioritise what they want.
DD knows that paying money for music and singing lessons means I can't afford other things she would like to do-but these are her choices and not mine.
I have found food is cheaper too-but only because we make food from scratch mostly now as 4 out of 5 of us are vegan. The girls have become excellent at cooking cakes etc if they want them! They know a great deal about nutrition too now. As teens they have eaten enormous amounts but I seem to remember dss doing the dame thing when he was a teen-he just did all of his eating after school!