It’s more than £30 to go to Stonehenge visitor’s center and catch an overcrowded shuttle to the actual monument (plus you have to pay to park in their field). However, you have better access and a better view, so weigh the alternative for yourself. To us, it wasn’t worth the seventy quid to get that close.
If you’re physically up for a two mile walk (which is actually quite pleasant), you can see it for free, which is what Beloved and I did. However, there are a few things you should be aware of.
Note… I visited in early September 2025. When you read this, things may have changed.
First, park in Larkhill, which is to the north of Stonehenge. Apparently, this is not a particularly popular thing with the locals (it’s a military base), but there it is. I don’t like people parking in front of my house, either, but I’m not in a position to stop them.
So you want to park on the edge of the road on Willoughby Rd, where I highlighted in yellow. Despite what Google Maps will show you in their satellite maps, there is NO access any closer than this. You’ll walk in the direction of the green arrow.

This is a north facing picture of the intersection of Willoughby and Fargo:

And I turned around and took a south facing picture:

For the non-Brit, it’s important to note the UK has a “Right to Roam” statute which allows walkers to meander across a wide variety of private land, such as the Salisbury Plain.
Note this does NOT include private residences, gardens and the like, fields growing crops or some other exclusions. However, you (and your leashed dog) are permitted to walk, at your own risk, around livestock.

However, if you bring Fido, make damn sure s/he is okay with the other animals BEFORE you go tromping around them. There is no grace for any dog who “worries sheep” (chases, barks at, frightens or worse).
Sheep are nervous animals to begin with and a barking dog can cause injuries from running away or a separation of a ewe from her lamb(s), which can result in the lamb’s death.
You’re risking having the dog put down, so if you have any concerns about your dog’s ability to be around other critters, for heaven’s sake, leave the pupper at home, and never, ever let them off leash. The farmer has the right to shoot the dog if they’re concerned it might harm their animals.
Also, it’s a criminal offense for you. Seriously not worth it.
Anyway, back to the walk.

Also, regarding that whole “right to roam” idea… there are gates in the fence along the Willoughby Road footpath and it is mighty tempting to take the shortcut shown in the photo above (note the circle with the cross through it) so you don’t have to walk as far.
DON’T DO IT.
You have a right to roam, but you do not have a right to a gate… nor do you have the right to “create” your own.

You can get into the field which allows you to shave off some yardage, but you cannot get back onto the footpath once you get close to the stones. You are stuck in the field with copious amount of sheep poo.

It appears people have climbed through the barbed wire fence at one spot, but I sure as heck wouldn’t do that – one, vandalism, and two, you wind up in the space where the English Heritage operates (the folks who charge you an obscene amount to look at the rocks).
Instead, follow the footpath as marked by the red arrows in that overhead view. It runs right alongside the path the paying customers take. You’re still set back a bit but not by much. Also, you can’t walk around the stones – you only get the one side to view.
If you want the whole visitor’s center experience, by all means, pay for it… but you won’t get much closer than if you take a walk. They don’t let you into the circle except on certain days and even then you need permission.

The footpath is the light brown dirt behind us. The blue-ish green path on the other side of the fence is the paid walkway, and you can see how much closer the paying customers get to stand.
Also, be aware the cheap method has no potties. If you need the lav, you’re outta luck. Your best bet is a byway rest stop on the A303 where they sell gas, convenience store items, and have bathrooms for you to use.
Alternatively, head into Amesbury where there’s an Aldi or a Tesco Superstore which will have bathrooms.