I laid down weed block fabric between my beds and rocked it. That's not as cheap as straw, but it's permanent and once you've done it, you never have to do it again. My garden is on a slight slope as well, and at first I'd worried that the rock would settle in the low spots. I used a crushed fine rock that compacts, so it's stayed put. My only complaint is that in the winter when it's wet, it will stick on our shoes--not good if you have hard wood floors or want to keep your sidewalk clean. I rectified the situation by adding a path of stepping stones from my sidewalk to the workshop, and I try to stay on them when it's wet.

It's also not a good solution if you plan to rearrange your garden and want to move your beds around. Mine are permanent so it wasn't an issue for me.

Here is a link that might be useful: my blog

Try putting down the cardboard and then straw on top of it.

I used a layer of weed block & then put down some DG (Decomposed Granite)

Both straw and hay have seeds but straw has much fewer. I've tried straw in my paths but it got tracked into the house all the time.

I use white dutch clover in my paths. It's nice to walk on barefoot but watch out for the bees. It seems to hold up to foot traffic okay.

I use chipped trees. I initially planned to keep it tidy by chucking the broken-down stuff in the compost and adding fresh
But after finding that the best parsnips, lettuces and silverbeet grow there, I'm much more casual about 'clean' paths.
Aesthetically, it's not to everyone's taste though...

Be careful if you decide to go the cardboard/straw route. I did that last year and the straw was incredibly slippery on the cardboard. It does work though...

In my garden (also a alight slope) I laid down cardboard and mulched over that with cheap shredded pine bark. It feels great under foot and doesn't slip around at all.

we had some 4x8 OSB sheets left from the construction project that got wet and were not usable in house, so -- in the garden they went. The space between our garden beds is about exactly 4ft. 3 years later - they are still there. Very easy to roll garden cart on it. Some weeds come up on the edges, when different pieces meet, but they get yanked.

So look around for a construction site, or find a local contractor/builder and ask them for any "spoiled" material.

Thanks for all the great suggestions. Paperfinch, is there any risk of the pine bark in the pathways leaching into the soil and making it too acidic?

No worries about the OSB and formaldehyde? I imagine it gases out to the atmosphere more than soaking into the soil but I'm just guessing.

I have both the wood chips and crushed rock and crushed rock (with plastic underneath) is a more permanent solution. The chips eventually make good soil and lots of thins grow there. Of course, I joined two beds for a large storage crops growing area in the wood chips garden. I could do it, but in the rock area the paths are permanent.

tlouise, I've been using shredded pine mulch in my garden for years and have not had any problems with too much acidity. It's a natural solution that will break down over time and feed the soil.

As an alternate, I've seen clover used in garden pathways and it always looks very lush, soft under foot, and doesn't take over like grass does. Maybe just an occasional weedeater, but relatively low maintenance. It's also an excellent cover crop for your raised beds.

re OSB sheets - the beds are raised garden beds and we grow good crops, so I guess it is fine. They were exposed to outdoor before - that's how they got bad/unusable.

tlouise pine bark will not make soil to acidic,that is an old garden myth.