Part of the problem is that RPGNow POD prices are behind the publishers only menu but here are some comparisons to illustrate why RPGNow PoD is a better deal and why Blackmarsh is not on Lulu.
Lulu only competes with RPGNow using Publishers Grade B/W only and it has minimum page count of 84 for both digest and letter.
84 pages is $5.01 letter size b/w on lulu
84 pages is $3.84 letter size b/w on RPGNow
200 pages is 7.10 on Lulu
200 pages is 5.30 on RPGNow
For color it there is no comparison RPGNow beats the pants off of Lulu
100 pages letter color is $25.50 on Lulu
100 pages letter color is $11.50 on RPGNow
For low page count it is even more silly
16 pages letter color is 8.50 on Lulu
16 pages letter color is 2.50 on RPGNow
In fact the only way a product with less than 18 pages for RPGNow is to use the full color option.
RPGNow is a better Print On Demand service than Lulu for RPGs.
Plus it appears their shipping is more reasonable especially foreign shipping.