I have been conducting an anonymous survey of picture book authors for several years now.  People send me information about their picture book advance, and I send back a report that details everyone's info, minus their names.  Survey respondents literally get to see what different houses offered for an advance and whether or not those houses agreed to more after negotiation.  They also get to see which houses offer escalation clauses.  Anyone who has a contract in hand can participate.  Click here for more info.

Meanwhile, here is some overall information, based on the data I have collected.

The following is based on information about 100 contracts, mostly dated 2004 or later

The mean (average) initial offer for the full sample of 100 deals is: $4,021.

The median (the point where half the offers are below and half are above) is: $3,250.

The overall mean final offer (after negotiation) is: $4,541.

The median final offer is: $4,000.

Breaking these numbers down by agented/unagented and first-time/veteran:

Unagented, first-time authors:

Mean initial offer: $2,007

Median initial offer: $1,750

Mean final offer: $2,125

Median final offer: $2,000

Unagented, veteran authors:

Mean initial offer: $3,304

Median initial offer: $3,000

Mean final offer: $3,405

Median final offer: $3,000

Agented, first-time authors:

Mean initial offer: $4,643

Median initial offer: $4,000

Mean final offer: $5,429

Median final offer: $5,000

Agented, veteran authors:

Mean initial offer: $6,238

Median initial offer: $5,000

Mean final offer: $7,505

Median final offer: $7,000