Just some comments & experience with FotoHub.
I had only been to FotoHub once for some scanning service and even though I am not a regular, they gave me a 10% discount when the amt came up to $70+. Since you're doing large no. of prints, getting 10% or more discount should not be a problem. Moreover, they do paranomic prints too (which you queried in another post) & I don't think they come cheap.
I've not done digital prints from them though, so dunno abt quality (although I've submitted some online & waiting for results).
I've talked to PhotoFriend too and they give discount /waive handling charge if your transaction is big. Since you're doing 100+ prints, sure can cham siong one
Quality-wise ... now, thats subjective ....