I've been asked to bid on a gig creating illustrations for a children's book but it's my first time doing this particular type of work and I'm not sure what would be a reasonable rate.

Specs are:
Digital illustrations 2400x2400 px
Full Color

Style Reference: Renee Magritte
http://www.atara.net/magritte/60s/song_of_love.html
http://www.atara.net/magritte/60s/blank-check.html
http://www.atara.net/magritte/50s/personal-values.html

Obviously not everyone would bid the same rate; time is more valuable to some than others. I'm looking for what would generally be considered a reasonable per-image rate. Or even tips on how I should go about coming up with my own rate. I don't want to ask for too much, but I gotta eat and pay rent, too.

Any advice from experienced pros would be greatly appreciated.

Thanks!