It depends on your community, obviously. $25 strikes me as very low but not unheard of, whereas $80-$100 strikes me as unreasonably high. Remember, we’re talking about limudei kodesh, not high-level physics or mathematics. I would have guessed in the $30-$50 range– but again, that’s based on my community only.
Homeschooling can be a great option for a large family, where the marginal cost of educating each additional child in a yeshiva day school can really take a financial toll. For a smaller family, less so. But it does depend on the earning potential of the homeschooling parent.
The social aspect is definitely very important, but I don’t think it’s impossible to make friends without going to school. You still have shul, youth groups, Yiddle League or other sports organizations, etc etc. If there are other homeschooling families in your neighborhood, you can organize gatherings with them. Also, some kids start out in school and then transition to homeschooling, in which case they have already made friendships that they just need to maintain. Or even if they were homeschooled from the beginning, it’s possible that they at least went to daycare or nursery and the parents can encourage those friendships to continue as well, as the children grow older. It’s very doable if you’re committed.