Others may disagree with my reasoning, but think of your's as a 340g system when shopping. That's 10% loss from your DT for rock etc, and your sump/frag added.
I agree a 180 won't cut it. Even a 280 would be undersized.
The nwb-250 doesn't list air, so I won't comment on it.
The cs12-2 may keep up if your system isn't heavily stocked, but I dont' see an air rating listed for it, so it's questionable.
The BM-180-cs may do the trick if you keep your stocking levels down, but may be undersized if you end up going full blown reef.
From what I've learned so far, any skimmer you choose that has low air input should have it's rating halved. The same is said of ones that don't list air flow ratings.
For example, I found a gently used skimmer rated up to 320g for my 110g system. I'm sure it's over-rated @ 320, but I think it can probably handle a heavily stocked 150g system.
Sorry I can't suggest any one specific model for ya, but I'd be inclined to pick one rated for up to at least 500g if you stay in the price range you've shown.
These are not suggestions, so don't buy them because of me. Just use them as examples of quality/price.
This is an example of what
may do the job for a decent price
http://www.reefshops.com/bubble-magu...n-skimmer.html
This an example of a good quality skimmer in
that other price range that would handle your system in it's sleep
http://www.jlaquatics.com/product/vt...0+Gallons.html