Yup
You're on target here on price. An ARM based tablet costs less to make than a Netbook... less RAM, cheaper processor, less storage, essentially the same LCD panel, less I/O, etc.
The main reason they have been expensive is the fact Apple lead the charge. Apple's always overpriced.. their cheapest laptop starts at $1000... the average laptop in the USA last year wnet for just over $500.
So sure, early models are going for higher profit margins riding om Apple's coattails. But the rise of Android is already ensuring PC-like competition in ths market.. both on price and features.
I want a tablet. What I want in a tablet isn't on the market yet, and probably will never come from Apple. But there's a good chance someone will meet my requirements this year, and at a lower price.
As for needing cellular... I don't think so. With all major smartphones supporting wireless tethering, it won't be neede.