We did $6 for the 1st tooth for DD1, the $5 was because it was the 1st.. and the $1 is a gold coin, tell you what that is the HUGEST hit there is!! DD2 lost hers while we were camping!!!! We knew it was coming, I packed a plastic easter egg to put it in lol borrowed tape from another family we were camping with (huge event lots of friends) but SHE got spoiled!!! The joke was the year before with DD1 a friend asked what the tooth fairy looked like at Pennsic (our camping event) and I jokingly said "She looks like YOU!" So when DD2 lost hers there the next year she got her normal TF$ but then that friend gave her another $5!!! lol (also had coins for DD1 as a gift, they are older coins that were her mothers, a sweet gift truly)
Now my cousin found a link to TF $ (dont know where) but that person took the glitter spray paint and glittered a dollar bill.. I thought that was a cute idea, but alas we had started the coin thing, AND I am allergic to glitter.. go figure..
But now that this answer is long, as long as you make it special it is a good amount. You want to do $1 for the 1st and then $.25 for each, why not? (you could even paint the $.25 with nailpolish lol)