Avoid the Chinese cr@ppers off eBay, they are absolute junk.
OP, stick with a genuine unit or get a decent name brand aftermarket unit. There are one or 2 genuine "2011 AVN" headunits on eBay from time to time (from private sellers, avoid the dealers, they want too much for them), you need to look carefully. The unit you want is similar to this;
The next thing to look out for is the part number. The ending digit refers to the illumination colour. You'll need green illumination to match your 50 series Camry illumination colour - green = PZQ60 00535. Cheapest I've seen one go for was around $450. Generally they'll sell for around $600-$700. The best thig about these is they are plug and play, no modifications required to the wiring whatsoever. 50 series Camrys utilise the newer plugs for stereos, particularly the antenna block connector instead of the old school coax connector.
You'll also need a new fascia - 200mm wide gap to suit 200mm Toyota headunits, part number = 55420 06050. Order from a Toyota dealer, should be around $60 retail.
If you want to go aftermarket, as I said before, stick with a name brand. I've fitted a Sony XAV-701BT to my wife's '12 plate Camry Hybrid, but a fair bit of modification is required. 180mm gap fascia from Metra in the US, along with wiring adapters, antenna adapter, Axxess ASWC steering wheel control interface. Yes it was a major mission, but we installed this unit to utilise MirrorLink to mirror our phone screens. Basically gives us Google Maps (or your favourite map app) plus just about everything else on the screen.