I've gotten answers like that before and it still just seems weird to me.
Like, I wouldn't call a landscaping company and offer them $300 to remove a tree from my property - I have no idea what it costs to remove a tree. If I say my budget is $300 and it actually costs $4,000 (which it does), I could fully expect them to laugh at me and hang up the phone.
I have neither gained nor learned anything.
When someone calls me and asks to play for their wedding, they don't tell me what their budget is - they ask me what I charge.
Maybe it was because my father needed a LOT of trees removed several years ago back when we lived in VT, but your $300 example was actually much closer to what it cost to remove trees completely (stump and all) for $1000. Ngl we would of actually laughed at any company that charges $4000 per tree as even without bulk charges, tree removals in most northeast states would still be about half that (and our guy even told us in his 30 years of experience that he knows a lot of friends that overcharge for tree removals knowing people who pay them aren't aware of how much it normally should cost.
Sorry, kinda tangent I know, but I had to constantly deal with landscape companies across several states and deal with tree removals due to carpenter ants.
Back on topic, Saying "$100 per character a reasonable price?" is hard to say as TC still never gave a full description I believe. An RTP style chibi sprite usually can cost you $10 to $25 + an extra $3-$5 for a downed matching sprite if you know who to ask/ where to look. Chibi RTP style battler
without any special animations would also be around $25,
with special animations, you're looking somewhere from $40- $50. Personally, I stick with Low for custom battlers which goes for even more than that as despite needing a lot, they really go a long way if you're making a more serious project.
16 faces personally seem overkill and I'd stick to 4 if this is your first project as I often see a lot of artists have a cheaper bundle option for 3+ expressions (including your default one of course), I personally use 8, but I have prior rpg maker experience plus set a small portion of my checks into the said project every other week to pace myself. If the topic creator isn't working, then I'd stick to just 4 and save a lot of money from the extra expressions.
Finally (before I run out of message space) image bust would probably range from $20 to $80 depending on quality and experience not including the extra expressions. The ideal is around $40 - $50 range as they produce high quality, but not overly detailed/ too realistic which suits most anime artstyles people often use in maker (including myself) imo. Helps to request "Thigh up" instead of "Full Body" and it mostly shows the entire character anyways, but at a slightly reduce cost which goes a long way.