alot would depend upon the original order and how it is worded. some orders make allowances for supprt during summer months when the child is with the NCP.
there are arguments for boths sides. the NCP claims that he has all of the expense during those months and shouldn't have to pay the CP during those months because she does not bare any expense for the children during that time. the CP claims that just because the child is not staying in the home during those months that the same bills still acquire. you don't necessarily have to quit paying rent, utilities, clothing, etc. i can see it from both sides.
transportation should have been addressed in the original visitation order. who is responsible? do you split the costs or does the father bare the costs? why the distance? did the dad move off or the mom?
if the mom was the one who moved off, he could request that she be responsible for the costs of the transportation or at least half or possibly for the costs to be adjusted in the child support amount, since the father did not have this expense before the mother moved off and he can not financially cover the expense. he should not be penalized (not seeing his son) because the mother chose to move.
if dad moved off - it's not fair to ask the mother to bare the cost of transportation for dad. again, she didn't have the costs prior to dad moving off. she shouldn't be penalized by reduction of support or baring half the costs of transportation. the move was not hers.
the visitations are not manditory. i could see were costs could be a problem. airplane tickets are not cheap. but if he doesn't exercise his visitation as much as possible then he doesn't have room for any complaints - change of visitation, reduction of support, anything that he wants to take back to court could be ripped apart by a lack of interest.
maybe you could try purchasing the tickets in advance, they are usually cheaper then. or maybe check out priceline.com and try to get a cheaper ticket that way. you can also run a search for discount airplane tickets. you will get several links that way. there are a few clubs that offer discount tickets and specials.