How much should I expect to pay for a Charles I and Elizabeth I shilling?

I would indeed recommend holding out for better examples without so much damage. "Honest wear" is one thing- and there is nothing wrong with buying low-grade coins as inexpensively as possible. But damage is another story.

(*Unless you're deliberately collecting damaged coins- like I do with holed pieces- and getting them at a steep discount.)

I'd try to go for something with better eye appeal, even if it's still low grade.

That being said, those coins you posted do still have some historical appeal. If they're cheap- really cheap- then sure, why not? Undamaged is better, but old beat-up coins can still have some appeal under certain circumstances. It is a matter of personal preference.

Your basic question about price is impossible to answer since there are so many different variables and types, not to mention different grades and "curveball" issues like the problems on the coins above.

It's kind of like asking "how much does a car cost"? Maybe somebody could give you a general range, like "oh, somewhere between five hundred and five million bucks", but it's an impossible question to answer precisely, because there are far too many variables.

I can certainly understand your interest in this era.

I chose a sixpence of Elizabeth I rather than a shilling, simply because I wanted a dated coin, and only the smaller denominations seem to have been dated.

After getting it slabbed, I'm into mine for about $270 USD. I bought it for the clear portrait, and the contrasting toning. It was a while before I found one that I liked that I could also actually afford.

England: silver sixpence of Elizabeth I, 1575, Tower mint, eglantine mintmark

 

And even if you don't want to or can't spend that much, there are more appealing "budget" examples.

 

Up to you. You'll not likely be getting any other Elizabethan silver for 30 bucks, without issues. If you're OK with the knowledge that these are "problem" coins and don't mind the damage in exchange for the relatively lower price, then OK.

I sold an Elizabethan piece for 20 bucks not long ago. I personally think it was better looking than that. However, it was a tiny silver penny, not a big shilling. So there ya go.