This might be a bit overkill but I image that this would indeed the best solution unless you want to run a wire between the buildings and keeping the cost down...
2 pcs - TP-Link CPE510 (Outdoor bridges)
http://www.newegg.com/Product/Product.aspx?Item=N82E16833704223
1 pcs - TP-Link TL-WDR3600 (Indoor AP)
http://www.newegg.com/Product/Product.aspx?Item=N82E16833704144
Run one cable from the FIOS router to one of the units and put it in AP Mode and mount it on the outside.
Mount unit #2 on the other building (put it in client mode) and run a cable to where the TL-WDR3600 will have good overall coverage. Put the TL-WDR3600 into AP mode (I have no idea if it works using stock firmware but it does work using OpenWRT) and you can additionally use at least 3 other ports for local devices if you need a small switch or so.
Shorter range units costs about the same and you can adjust transmit power anyways, the WDR3600 is to keep the costs down and if you decide to go another route be sure to grab a dual band AP as 2.4Ghz might be very crowded.
UBNT does have a similar solution but they're much more expensive, the TP-Link devices should perform very similar as they also use Atheros chipsets.
//Danne
2 pcs - TP-Link CPE510 (Outdoor bridges)
http://www.newegg.com/Product/Product.aspx?Item=N82E16833704223
1 pcs - TP-Link TL-WDR3600 (Indoor AP)
http://www.newegg.com/Product/Product.aspx?Item=N82E16833704144
Run one cable from the FIOS router to one of the units and put it in AP Mode and mount it on the outside.
Mount unit #2 on the other building (put it in client mode) and run a cable to where the TL-WDR3600 will have good overall coverage. Put the TL-WDR3600 into AP mode (I have no idea if it works using stock firmware but it does work using OpenWRT) and you can additionally use at least 3 other ports for local devices if you need a small switch or so.
Shorter range units costs about the same and you can adjust transmit power anyways, the WDR3600 is to keep the costs down and if you decide to go another route be sure to grab a dual band AP as 2.4Ghz might be very crowded.
UBNT does have a similar solution but they're much more expensive, the TP-Link devices should perform very similar as they also use Atheros chipsets.
//Danne