No prices here, but if you want a (mostly?) complete list of contents, release dates, etc., the wiki page is pretty well kept up
https://en.wikipedia.org/wiki/Marvel_Omnibus
The nature of it being a giant table means it's all on one page and can be easily searched, but you won't get info about out-of-print, etc.
As for what to get, every few weeks someone lists all the Marvel omnis that are out of print, have low stock, or are readily available. I tend to jump on whatever looks good in the "low stock" section before it disappears and becomes incredibly expensive.