Hello Andy,
I'm not the one who gave you a figure for sales through LuLu, but I do know
a little bit about them.
I belong to The Society of Children's Books Writers and Illustrators
(SCBWI), an organization for professional children's writers. At the SCBWI
site there is a section where members discuss self publishing. LuLu is
frequently the subject and so far there are only positive things said about
the POD publisher.
The key to selling any book now - even if a publishing house picks up your
book - is marketing, marketing, marketing. Anyone who wants to sell books
must make it their "job" to line up book signings, have announcements
published in newspapers, have reviews published, etc.
There are many self publishing/POD agencies and some don't have the best of
reputations. LuLu - so far - has a good reputation.
Friends have published books through various methods including the
traditional publishing houses and every method of self publishing and POD
publishing there are. All have to work very hard at promoting their books.
I know this isn't much, but maybe it will help you a little.
Mairlyn