It is hard for me to compare the prices, and some of these look very overpriced it seems compared to here in the US.
Here is what I think you should consider...
The Skyzone SKY03O are very nice and have very good features, the only downside is being limited to the built in receiver, it is good, but not great.
HDO's should be about $400 US since the HDO2's are selling for $500 US, that is what I see here in the states, but it seems they want the same amount for both on the one website.
Some people have trouble with the HDO2 since the focus adjustment which accounts for bad vision can cause the optics to be very close to the eye and their eyelashes rub up against the lens, sometimes a thicker face plate foam can eliminate that issue, and some don't care if their eyelashes touch.
A lot of people who don't like they eyelashes touching have chosen to go with HDO's and use the diopters we have been using for years (since HDO2 has no ability to use them, that is what the focus adjustment is for).
You will also want a good set of antennas for your goggles, none of them come with good ones, if they come with any at all. Depending on what you buy you will want 2 good Omnidirectional and 1 directional (patch) antenna, and they are not cheap either, figure about $20 US a piece for each. The best Omni you can get if you can find them are the VAS Ion Pro, or if you can afford it the VAS SkyHammer. With patch antennas there are many good ones.
There are other brands of antenna that are also very good, on a quad you need durability, but on the goggles they do not need to be durable since you wont be crashing your goggles into the ground.
It will also depend on what kind of antenna is on your quad, you will want to go with RHCP (Right Hand Circular Polarized) or LHCP (Left Hand Circular Polarized) but I would pick RHCP since they are more widely available.
Either of the polarized antennas will work fine with NON circular like Dipole antennas on the quad which is what most of the small ones come with.
Let me know what you are thinking for Goggles, a Receiver if they don't have a built in one, and what antennas, and I will give advice.
Other good names to look for in antennas is Lumenier AXii 2, TrueRC, Menace, or ImmersionRC.