One thing to remember is that, since the Elige is a road car, we have an air bag. Head and neck restraints work extremely well in certain circumstances and not as well in other situations. If you run through the likelyhood of accident type and the resulting injuries in driving events of various sorts you could rank the safety measures acceptable to you and the managing organization.
For example, I raced in SCCA in a showroom stock class and one car I drove, a VW GTI, had a ten gallon gas tank made of plastic. Many drivers in the cheaper, I mean less expensive, classes ran a Nomex suit and underwear, two or three layers. Of course the Formula Atlantic guys, with a seven gallon fuel cell in a monocoque tub wore three layer suits and undies. Which fuel system would you say would most likely be compromised?
The need for a Hans, IMHO, is much less than having a great set of belts first, and probably less than the need of having a flame retardant suit. The severity, frequency and angle of impact, the type of belts used, etc. would all make a head and neck restraint more or less effective. An airbag would have a range of effectiveness as well. IMHO $500-600 would be better invested in a fire retardant suit and accessories more so than in a head and neck restraint. Use as much safety equipment as you are required to have and wish to use.
I asked this before a year or so ago: Would you drive on the track with a 1950s, 60s, etc. level of protection? A track day has risks whatever the level of equipment you employ. How much of a risk will you take?
I drive in a polo shirt and slacks/jeans with six-point belts, helmet and hand-held fire extinguisher. Risky? Yes. I would choose to drive, rather than not, even if I had to do without seat belts. (Where is my mid-sixties GP car? I parked it here somewhere.) The next level of protection I would invest in would be a fire resistant suit, gloves, socks, etc. before additional restraints.
My intent isn't to flame safety advocates, but just to point out that there are varying levels of acceptable risk. I've ridden and raced motorcycles and wouldn't do without a helmet, boots, gloves, and a jacket. When I rode on the road in jeans, rather than in leathers, I knew it was risky and it made me very uncomfortable. But, even in full race leathers you can be squashed by a vehicle on the road or track. The risks are there. Do you take them?