I used local net prices, multiplied by $FX rate, TX Power from tech specs. If I got this right RB R52nM has the best price/power ratio.
Approx price:
1. RB R52nM (35$)
2. RB R52HM (45$)
5. DBII F50N (51$)
3. UBNT SR71-15 (81$)
4. UBNT SR71-A (107$)
MCS7 20Mhz 802.11n 5GHz Tx Power:
1. DBII F50N (20dBm)
2. UBNT SR71-15 (19dBm)
5. RB R52HM (18dBm)
3. RB R52nM (16dBm)
4. UBNT SR71-A (15dBm)
Ratio:
1. RB R52nM (2,2 $/dBm)
2. RB R52HM (2,5 $/dBm)
5. DBII F50N (2,6 $/dBm)
3. UBNT SR71-15 (4,3 $/dBm)
4. UBNT SR71-A (7,1 $/dBm)