Is there currently scientific equipment that’s able to measure how much pheromones are in the air to see how the amount of pheromones differ from person to person?
I don’t think so. I haven’t heard of anything like that. Perhaps in a closed lab somewhere they might be able to test the sweat and pee of people to properly determine who is emitting what. It’s a good question though, but I think science hasn’t quite caught up yet.
Is the problem a lack to invest money into building such a thing or the problem that the amount of pheromones in the air is too low?
In addition to difference between person I think it would be interesting to know how much the amount of pheromones that get emitted differs from moment to moment.
Our bodylanguage can change very drastically from moment to moment. Am I right to say that it’s then an unsolved question whether the amount of pheromones that gets emitted changes as dynamically as bodylanguage or whether it’s more static?
Well I think it would be cool if we could get James K in here to answer these questions from a scientific standpoint 
The following citation discusses measurement of axillary odor production in different people. No one but me and my colleagues has shown that the chemicals in axillary odor are human pheromones, and we have not yet published our findings. So currently, this published work comes as close as any I know about to answering the question about measuring the pheromones in the air.
The collection method employed by Martin et al. (2010) used exercise to
collect mixed axillary sweat, yielding a combination of fluids from eccrine,
apocrine, and apoeccrine glands…
• Axillary odor is determined by variants in the ABCC11 gene, which
encodes an ATP-driven efflux pump protein.
• Individuals who are homozygotic for a SNP (538G>A) in the protein’s
polypeptide chain have significantly less of the characteristic axillary
odorants.
• The 538G>A SNP predominates in Asians who have nearly complete loss
of typical body odor.
James V. Kohl
I knew we could depend on JK 
I will add that pheromone enhancement works when lower levels of natural pheromone production are insufficient to elicit a higher level of interest. But other unpublished work that was done to determine whether fragrance positively affected the perception of axillary odor* suggests that pheromone-enhanced fragrance products will work better than the pheromones alone. When someone is trying to elicit positive affects on others that cannot be attributed to fragrance, products without fragrance be appropriate as they would in fragrance free working conditions.
*Do perfumes mask or interact with body odour? Lenochova et al (2008) ISHE, Bologna
James V. Kohl
http://www.pheromones.com
Yes but its not an easy operation.
In our work, we use a pump-driven suction device to gather air samples from a human subject who is loosely wrapped in a space blanket with holes cut at the various measurement points.
The samples are then sealed and sent for mass spectrometer analysis and the phero compounds and individual profiles are identified/isolated from that.