artists_beware | Quality postcard print-on-demand services?

EDIT: ADDED PROOF/PRINT SCAN FROM MOO

This was the first place I could think of for advice on where to get good prints! Basically I am looking to get some postcards or greeting cards made of my photos to sell at cons. I tried a small run with Overnight Prints and while the price is great, the quality is not quite what I was hoping for. It's not terrible I'm just picky. I've tried to show the quality by posting part of the file I submitted and then a scan of the card next to it. Keep in mind this is 300dpi blown up to 72 dpi for the web, and that my scanner may be upping the contrast a little. It's not bad, but I've seen smoother prints!

proof vs print:

Here is what overnightprints looked like (proof on left). Note the sales reps assured me that the greeting cards get the "quality" print, not the "value" print

Here is what Moo looks like:

Thoughts so far:
I'm not sure if the resolution is really better with Moo, but I would say the print is definitely smoother. My biggest problem with the OvernightPrints order was you could see faint vertical lines where I guess one of the print heads was doing something a little different from the others. Moo cards do not have that!
However, Moo cards are a lot more expensive. I paid $1 each for a run of 10 from overnight prints ($1.36 each including S&H) vs $1.20 each for a run of 25 from moo ($1.54 including S&H). Doesn't sound so bad except that if I bumped up my size to 250 from overnight prints it'd be $0.22 each from overnight prints before S&H, vs $1.23 for 250 Moo cards. Maybe I can reduce that to $0.86 with a coupon... but the S&H is huge! Moo's site says the S&H for the 250 cards will be $47.75, vs OvernightPrints economy shipping is just $7.75 (economy takes 3 weeks however - the shipping option on overnight prints that takes two days [about what my Moo order took] is still $33.59)

The upshot of Moo is that you can put many different designs in your order, vs each run with overnight prints is a single image.

Conclusion: Moo's quality is a bit nicer but the cost is prohibitive for the prices I wanted to sell for, even with a large run. I'm going to try a few other places.

So, my question is, where does one get nice postcard prints? I get the feeling this level of quality is fairly standard for most print on demand places hence I'm hesitant to just keep ordering small runs willy-nilly!

Recommendations much appreciated :)