I paid for everything in one payment right before he shipped them so I never had an issue with him adding extra costs.
His fees are a little on the high side, but he does a really good job so I don't mind paying.
This is his bill for me from last time.
6 bettas x 15$ = 90$ ( shipping cost from Thailand to me + airport fee and custum clear...)
+ 40$ for nextday delivery to your address
+ 10$ for safe box
+10$ for heat pack( don't worry, i use the best heat pack, 72 Hours )
Total: 150$ + 4% for Paypal: 6$
Grand total: 156$
Your cost sounds about the same as what I payed, I think the $20 includes the box and packing as well as the heat pack.