I bought $50 Eachine 800’s, they have been really good. By all means drop $500 on HDO2’s but as noted above the technology has entered a state of flux right now, DJI have shaken the market up with their HD digital system, which makes high end analogue goggles a gamble right now.
For fixed wing a decent all in one camera and VTX with a omni antenna and a set of goggles is all you need to try it out, the AOI’s can easily be moved from plane to plane and a 200mw one will be powerful enough to get decent reception over a fair distance, especially in open country.