Experienced Authors - am I selling myself short, or just right?

For lots of 10 or more, boxed together, I have seen discounts between 10-50% plus shipping.

1) Why doesn't the library want to buy the books through the normal distributor? It would be better for you because you'd get royalties (and a better record of sales). If you buy them at your discount and give a discount to the library, you may not make anything on the sales. Sounds kind of strange for a library to want to buy out of a car trunk.

2) Big time authors get outrageous fees for appearances, but certainly not to high schools. In fact, I'd be surprised if many high schools would be able to afford any appearance fees for guests in these days of tight budgets, and if they did, it would be for someone with some degree of celebrity. Do you fall in that category? In my day job, I occasionally make high school visits, but it is called outreach and it is done gratis. It's considered a donation to the local community. $150 for a high school visit? This sounds kind of strange to me as well. Good luck getting any bites. Are you a well known author (like with books on best-seller lists)? If not, your moniker may be appropriate. Keep in mind that public schools across the country are having to drop extracurricular activities related to the arts (and even some electrive classes in the arts) because of tight budgets.

NOTE added in edit: I've had local teachers ask if I'd be interested in talking to their classes about creative writing, and it was clearly understood on both ends that it would be a volunteer thing (the outreach type of arrangement).

By the way, it took me 10 minutes to think about and compose the anwer to your original post. You owe me $33.33.

Oh, you mean I shouldn't charge a fee for making an appearance here to talk about writing? (This is a joke, but with a point)

I've visited high schools for free, but it's not improper to receive payment for a visit that is going to take a lot of time/go into the evening hours/etc. A lot depends on what the school's expectations are, whether the school board has budgeted for speakers and how much, etc. The only time I've been paid for a school visit so far was for a standing visiting authors program the school had; I accepted without even knowing there was a fee, but I received $350 for it. (But that was a very well-funded program.) I think you basically have to know if the high school has a history of that, and what their resources are. You definitely don't want to charge a school in need, particularly as the visits work to your advantage; however, there's also no point in turning down money the school is prepared to pay you.

Are we talking about fiction or non-fiction here? It makes a difference. You don't have to mention anything that would identify you or the book if you don't want to, but for all of the people who read here (myself lincluded), the kind of writing would be good to know. Non-fiction authors of notable expertise can more easily garner fees for appearances. If fiction, I suspect it's YA, but I'd still be surprised at appearance fees like you mentioned from public schools. If you can swing that, though, more power to you.

What are the venues? Schools? Private or Public?

The school that paid me was a public school, and I also write YA fiction.