Great! I'd love to see more D20 Modern material.
My wife put out Modern Backdrops through RPGObjects, and it sold well enough through RPGNow to have a print run (it's back from the printers, and has been spotted and bought off of store shelves!!!).
My advice is to put out the Modern product you would buy, and go from there.
I should have clarified the "sight unseen" comment.

My bad. What I'm talking about there, is "I'll put out a D20 Modern product if 150 people swear they'll buy it."
Uhhhhh..... Oooookay..... What will it be? What's the focus of the book? Will it have crunch? Will it have fluff? Will it be useful?
You're asking people to swear to buy a product about which they know nothing except it's to be for D20 Modern... Not that you'd do this, but that could mean you'd be putting out.... ...... Modern Crapmasters The D20 Modern Guide to Septic Tank Maintenance and Pumping, complete with the Crapmaster Advanced Class.... Have it as a 10 page PDF for $29.95, and expect those 150 people to make good on their promise.
That's what I mean by not committing to anything sight unseen.
Looking forward to seeing what you have to put out...
Just as a bit of input, however, I'll take a look at the paladins and priests, and look at the blurb.... But something like THAT doesn't sound like it's up my alley.
I'd rather see fully modern material, rather than converted fantasy classes, but that's just me.
Unless you're looking to completely revamp the classes for fantasy, and thus make it easier to port D20 Modern to the fantasy genre, using the D20 Modern mechanics for fantasy... That would be cool.