I have been using Lulu for about six years now. A word of caution regarding ISBNs. An ISBN changes the nature of the earnings you make from selling a book for tax purposes. I could only ever afford an ISBN once so mostly I have done without. Ironically this means that if people buy most of my books I get my money in the UK sent to me. If I sell copies of the ISBNed one I have my earnings held hostage by the IRS until I pay a notary in this country to countersign some ridiculous document stating that I don't make money in the US and therefore don't have to pay taxes in the US.
You are probably in the US yourself but the distinction remains, selling book-shaped objects that are not officially books because they have no ISBN does alter the way that the IRS views taxation on those products. So you might want to look into the tax implications of sale for US residents.
As to Lulu itself the core publishing part of the business has come on in leaps and bounds since 2005 and its five step publishing wizard is pretty awesome, however I would have couple of goes with it before you try something you actually want to have published just to get used to how it all works. It allows you to download preview PDFs to check everything looks okay.
The customer service at Lulu is pretty terrible or at least it was the last time I needed anything and their knowledge base/support section is needlessly arcane and ridiculous. The best policy I have found is to have a go at something and see if it works. If it's something important Google "Lulu (your question)" and Google may assist you in mining information out of the broader internet where Lulu have failed.
I have been setting some Role Playing Game products over the last couple of years and Lulu's multiple PDF upload wizard, cover designer and their support for extravagant page layouts have all been very useful.
Createspace, as mentioned by Steven above, I only checked out when it was brand new and back then it was pretty ropey. It forced you to have ISBNs even if, as in my case, you didn't want them. Also at that point they had no UK printers which Lulu got about three or four years ago. These are selling points that I'm sure are irrelevant to you. I'd guess that the poor binding and muddy print quality issues Createspace had when they first started are now also a thing of the past but I mention them because when I checked out the service people were not happy about these things.
EDIT: BTW making the PDFs and stuff is free. You only pay for something when you want printed copies of it, for the paper and delivery and stuff. Example price 200 page crown quarto is about $3.50 don't know about US Delivery costs but over here it's a bit more like $5 P&P for courier delivery.