Bookshelf speakers on a bookshelf?

I'm in a bit of a bind when it comes to speaker placement. I'm cobbling together a system for a friend, but the only place she has to put the speakers is in a bookshelf (stand-mounting is absolutely not an option, nor is floor-standing speakers). It's a 10' x 12' home office, and she'll be listening from her desk. The speakers can be placed in a bookshelf at ear-height.

I'm aware that bookshelf placement will kill the soundstage, but alas, such is life.

I've purchased a Linn Classik integrated/cd player for her (used, thank you Audiogon!). It has 75 watts into 4 ohms.

I'm thinking that speakers with front-firing ports would be best, but I'm open to all suggestions.

The other consideration is frequency response. I'm definitely intersted in speakers that go low - below 50 hz - (e.g., Silverline, rear-firing port). The Classik, however, has tone controls, and I could possibly use them boost the bass a bit. My price range is about $500 - $800, used.
All your thoughts and comments are welcome.
Thanks for your help.
I was just eyeing the Silverline SR12 monitors for sale on this site--about $500 and very fine, small monitors. Other thoughts: Mission m71 just reviewed in this month's stereophile, they are only about $250; Mirage 90i for sale used on this site for really cheap, I think $200. I have had a pair of the Mirage for about 10 yrs and they are amazing quality for small speakers without sub. I have my Mirages on a bookshelf in a spare bedroom and they still sound good, given the circumstances.
I use a pair of Castle Isis bookshelf speakers which are designed for close-to-rear wall placement as a second system with a Magnum Dynalab reciever, and they sound fine when placed in this manner. How strong are they below 50 Hz?....certainly adequate for the purpose you outline. These are discontinued and I got them on sale from eAudio net.
Linn Tukans work well on a shelf and close to rear wall. They are discontinued, but come up on Audiogon occasionally. Also consider Linn Kans or Katans, current bookshelf models. Linn electronics work best with Linn speakers and they are not fussy about placement.
I don't have huge experience with bookshelf speakers, have used about 6 pair over the last 20+ years in various bedroom, office...etc. situations.

The best sound I have heard with a bookshelf speakers used in a bookshelf are the ones in my sons room, the KEF Q15.2. I would not have thought..but these little guys sound great.

I was in a situation where I needed to take his system to a friends home for an event..and the system ended up being used in a very large area with high ceilings..and they did the job well. They are also price effective. Worth a listen, if you have the chance.

You might want to check some of the reviews on on any of the above suggestions.

Good luck.
Thanks, guys. You've given me terriffic food for thought.
I'm in a similar situation. My only additinal advice would be to avoid and ported speaker for the bookshelves.
Ls3/5s are great little speakers. I'd add to trebleclef to avoid any speaker with an emphasized bass response, since it will be even more emphasised by shelf placement. Ideally demo as will be used.