Here are most of the BLE chips I know:
TI CC254x: old, well known, power efficiency is not great, extremely widely used. CPU is weak (not ARM). power: 27mA@any supply voltage, size: 6x6mm, price: $1.95.
nRF51822: newer, excellent, good if a non-realtime MCU is needed, power: 8.0mA@3V, size: 3.5x3.8mm (more commonly 6x6mm), price: $1.92.
nRF8001: newer, excellent, good if you don't want to develop firmware; essentially same as above
Broadcom BCM20732: very new, good but support is lame, also good if non-realtime MCU is needed
ST BlueNRG: very new, looks good from datasheet, power: 8.2mA@3V, size: 2.66x2.56mm, price: $1.45
Dialog DA14580: very new, looks excellent from datasheet. power: 4.9mA@3V, size: 2.5x2.5mm, price: $1.68.
I've already got a micro on the board so I don't really need another SoC. A BLE radio would suffice.
It seems that nRF8001 and nRF51822 (for example) only differ in that the firmware is burned in (not upgradeable, fixed function) on nRF8001; almost everything else about these chips is the same, leading to the supposition that they are built on either exactly the same, or almost the same, silicon. So there is no savings in power, part count, etc; there may be savings in ease of development (don't need to use the BLE stack, can use commands to control the device from another MCU).
Given that iBeacons are just transmitters, are there any BLE radios that do not have the RX capability (which would hopefully translate to lower costs)?
No, sorry; many things in the BLE standard require two-way communication.