ok, here are several options ....
First have you checked to make sure your have the latest foscam firmware? IF you are happy with the image, then that might be the cheapest route...
The hikvision DS-2CD2532-I(S)(W) http://www.hikvision.com/en/products_show.asp?id=9446 is wifi. Note that to get audio and wifi you MUST order the SW version, meaning you need to specify audio and wireless. You will probably need to lower the resolution to 2mp and the bitrate a bit if you are going wifi, depending on your network. This camera also has the capability to record to an internal up to 64gb sd card. That way even if your wifi goes out, it records as long a the camera is getting power. The wifi version is not available from us resellers. You must order from aliexpress. CCTV China has been proven to be a reliable source http://www.aliexpress.com/store/product/2014-New-Hikvision-dome-camera-DS-2CD2532F-I-S-W-audio-Wifi-3MP-Mini-dome-Up/638300_1679331340.html
The camera is available with several lenses. 2.8 (widest view) 4mm(medium, standard) and 6mm and 12mm (narrowest view). Make sure you specify the one you want, probably 2.8 or 4mm. These cameras have so much resolution the 2.8 is really nice and you get lots of coverage. Also make sure to specify english firmware.
Also, while you may not be able to run cable to that location, it is very likely that a professional could. You might want to look into hiring someone just to run the cable. All you need to run is one ethernet cable as the hikvision is POE and can carry power and data over the same cable. You would be surprised at how well and neat these guys can run cable. They can bury it. Wifi is always a hassle. Particularly with HD cameras.
Finally have you considered using non wireless camera with a powerline adapter? Does the garage share a power panel with the home?