I have used the D-Link DWS2100AP in similar situations quite a number of times. They have a wireless setting "WDS with AP". It creates a "hopping" between AP's so that they don't all need to be connected via ethernet cables. It's a bit tricky to get right, but it works very well if you do it right.
Don't skimp on the amount of AP's though. To set up WDS you need at least 60% signal strength between AP's. You should consider 8dB omni-directional signal strengthening antenna's instead of he standard little antenna then your distance between AP's can tripple.
Pointers on setting up WDS: First set up SSID's and WLAN security identically (including admin password). Then set up WDS (basically just mapping MAC's between AP's that connect. Do not create loops! The WDS-2100AP does not support redundancy. If you have a loop in your network it will fall apart.
