We've got 3 raised garden beds, roughly 4'x6' each.

Recently planted some herbs in pots on our deck and it looks like at least one of those pots has already been ransacked for seeds.

We've got crows, squirrels and rabbits at the very least in our yard.

Before planting everything else in our garden (tomatoes, peas, radishes, peppers, green onions), can you give me some suggestions for fencing? Preferably affordable.

One of the beds already has some 1x2s around it that the previous owners must have used for fencing, but none of the fencing is up.

What's an effective way to fence these things in, especially to keep out the birds and the squirrels?

Screen material like you'd use on a patio. It comes in a widths that would cover the entire top. Sun can pass through it as well as light.

Hardware cloth or chicken wire/poultry netting. They’ll eat through screen material. At least they do here. Fasten it down at the edges.

Poly bird netting will work too, unless it's rodents that are willing to chew through it.

Screen the bottom foot or so and poly above that. I wouldn't use screen or hardware cloth for the whole thing unless I absolutely had to due to expense and the fact that it's a pain in the ass to work around/over.

I use a motion sensor sprinkler to discourage the critters. Before placement, the deer would regularly destroy my tomato crop, the last two years there has been no predation at all.